We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
sandbox decorator not working on py3
run:

```
python3 kivy/kivy/uix/sandbox.py
```

result: 

```
Clock.tick()
File "/usr/lib/python3.4/site-packages/kivy/clock.py", line 483, in tick
 self._process_events()
File "/usr/lib/python3.4/site-packages/kivy/clock.py", line 615, in _process_events
 event.tick(self._last_tick, remove)
File "/usr/lib/python3.4/site-packages/kivy/clock.py", line 353, in tick
 callback = self.get_callback()
File "/usr/lib/python3.4/site-packages/kivy/clock.py", line 320, in get_callback
 return callback()
File "/usr/lib/python3.4/site-packages/kivy/weakmethod.py", line 47, in __call__
 return getattr(self.proxy, self.method_name)
AttributeError: 'Sandbox' object has no attribute '_f2'
```


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `kivy/uix/sandbox.py`
Content:
```
1 '''
2 Sandbox
3 =======
4 
5 .. versionadded:: 1.8.0
6 
7 .. warning::
8 
9     This is experimental and subject to change as long as this warning notice
10     is present.
11 
12 This is a widget that runs itself and all of its children in a Sandbox. That
13 means if a child raises an Exception, it will be caught. The Sandbox
14 itself runs its own Clock, Cache, etc.
15 
16 The SandBox widget is still experimental and required for the Kivy designer.
17 When the user designs their own widget, if they do something wrong (wrong size
18 value, invalid python code), it will be caught correctly without breaking
19 the whole application. Because it has been designed that way, we are still
20 enhancing this widget and the :mod:`kivy.context` module.
21 Don't use it unless you know what you are doing.
22 
23 '''
24 
25 __all__ = ('Sandbox', )
26 
27 from kivy.context import Context
28 from kivy.base import ExceptionManagerBase
29 from kivy.clock import Clock
30 from kivy.uix.widget import Widget
31 from kivy.uix.floatlayout import FloatLayout
32 from kivy.uix.relativelayout import RelativeLayout
33 from kivy.lang import Builder
34 
35 
36 def sandbox(f):
37     def _f2(self, *args, **kwargs):
38         ret = None
39         with self:
40             ret = f(self, *args, **kwargs)
41         return ret
42     return _f2
43 
44 
45 class SandboxExceptionManager(ExceptionManagerBase):
46 
47     def __init__(self, sandbox):
48         ExceptionManagerBase.__init__(self)
49         self.sandbox = sandbox
50 
51     def handle_exception(self, e):
52         if not self.sandbox.on_exception(e):
53             return ExceptionManagerBase.RAISE
54         return ExceptionManagerBase.PASS
55 
56 
57 class SandboxContent(RelativeLayout):
58     pass
59 
60 
61 class Sandbox(FloatLayout):
62     '''Sandbox widget, used to trap all the exceptions raised by child
63     widgets.
64     '''
65 
66     def __init__(self, **kwargs):
67         self._context = Context(init=True)
68         self._context['ExceptionManager'] = SandboxExceptionManager(self)
69         self._context.sandbox = self
70         self._context.push()
71         self.on_context_created()
72         self._container = None
73         super(Sandbox, self).__init__(**kwargs)
74         self._container = SandboxContent(size=self.size, pos=self.pos)
75         super(Sandbox, self).add_widget(self._container)
76         self._context.pop()
77 
78         # force SandboxClock's scheduling
79         Clock.schedule_interval(self._clock_sandbox, 0)
80         Clock.schedule_once(self._clock_sandbox_draw, -1)
81         self.main_clock = object.__getattribute__(Clock, '_obj')
82 
83     def __enter__(self):
84         self._context.push()
85 
86     def __exit__(self, _type, value, traceback):
87         self._context.pop()
88         if _type is not None:
89             return self.on_exception(value, _traceback=traceback)
90 
91     def on_context_created(self):
92         '''Override this method in order to load your kv file or do anything
93         else with the newly created context.
94         '''
95         pass
96 
97     def on_exception(self, exception, _traceback=None):
98         '''Override this method in order to catch all the exceptions from
99         children.
100 
101         If you return True, it will not reraise the exception.
102         If you return False, the exception will be raised to the parent.
103         '''
104         import traceback
105         traceback.print_tb(_traceback)
106         return True
107 
108     on_touch_down = sandbox(Widget.on_touch_down)
109     on_touch_move = sandbox(Widget.on_touch_move)
110     on_touch_up = sandbox(Widget.on_touch_up)
111 
112     @sandbox
113     def add_widget(self, *args, **kwargs):
114         self._container.add_widget(*args, **kwargs)
115 
116     @sandbox
117     def remove_widget(self, *args, **kwargs):
118         self._container.remove_widget(*args, **kwargs)
119 
120     @sandbox
121     def clear_widgets(self, *args, **kwargs):
122         self._container.clear_widgets()
123 
124     @sandbox
125     def on_size(self, *args):
126         if self._container:
127             self._container.size = self.size
128 
129     @sandbox
130     def on_pos(self, *args):
131         if self._container:
132             self._container.pos = self.pos
133 
134     @sandbox
135     def _clock_sandbox(self, dt):
136         #import pdb; pdb.set_trace()
137         Clock.tick()
138         Builder.sync()
139 
140     @sandbox
141     def _clock_sandbox_draw(self, dt):
142         Clock.tick_draw()
143         Builder.sync()
144         self.main_clock.schedule_once(self._call_draw, 0)
145 
146     def _call_draw(self, dt):
147         self.main_clock.schedule_once(self._clock_sandbox_draw, -1)
148 
149 if __name__ == '__main__':
150     from kivy.base import runTouchApp
151     from kivy.uix.button import Button
152 
153     class TestButton(Button):
154 
155         def on_touch_up(self, touch):
156             #raise Exception('fdfdfdfdfdfdfd')
157             return super(TestButton, self).on_touch_up(touch)
158 
159         def on_touch_down(self, touch):
160             #raise Exception('')
161             return super(TestButton, self).on_touch_down(touch)
162 
163     s = Sandbox()
164     with s:
165         Builder.load_string('''
166 <TestButton>:
167     canvas:
168         Color:
169             rgb: (.3, .2, 0) if self.state == 'normal' else (.7, .7, 0)
170         Rectangle:
171             pos: self.pos
172             size: self.size
173         Color:
174             rgb: 1, 1, 1
175         Rectangle:
176             size: self.texture_size
177             pos: self.center_x - self.texture_size[0] / 2.,\
178                  self.center_y - self.texture_size[1] / 2.
179             texture: self.texture
180 
181     # invalid... for testing.
182     #on_touch_up: root.d()
183     #on_touch_down: root.f()
184     on_release: root.args()
185     #on_press: root.args()
186 ''')
187         b = TestButton(text='Hello World')
188         s.add_widget(b)
189 
190         # this exception is within the "with" block, but will be ignored by
191         # default because the sandbox on_exception will return True
192         raise Exception('hello')
193 
194     runTouchApp(s)
195
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/kivy/uix/sandbox.py b/kivy/uix/sandbox.py
--- a/kivy/uix/sandbox.py
+++ b/kivy/uix/sandbox.py
@@ -24,6 +24,7 @@
 
 __all__ = ('Sandbox', )
 
+from functools import wraps
 from kivy.context import Context
 from kivy.base import ExceptionManagerBase
 from kivy.clock import Clock
@@ -34,6 +35,7 @@
 
 
 def sandbox(f):
+    @wraps(f)
     def _f2(self, *args, **kwargs):
         ret = None
         with self:

{"golden_diff": "diff --git a/kivy/uix/sandbox.py b/kivy/uix/sandbox.py\n--- a/kivy/uix/sandbox.py\n+++ b/kivy/uix/sandbox.py\n@@ -24,6 +24,7 @@\n \n __all__ = ('Sandbox', )\n \n+from functools import wraps\n from kivy.context import Context\n from kivy.base import ExceptionManagerBase\n from kivy.clock import Clock\n@@ -34,6 +35,7 @@\n \n \n def sandbox(f):\n+    @wraps(f)\n     def _f2(self, *args, **kwargs):\n         ret = None\n         with self:\n", "issue": "sandbox decorator not working on py3\nrun:\n\n```\npython3 kivy/kivy/uix/sandbox.py\n```\n\nresult: \n\n```\nClock.tick()\nFile \"/usr/lib/python3.4/site-packages/kivy/clock.py\", line 483, in tick\n self._process_events()\nFile \"/usr/lib/python3.4/site-packages/kivy/clock.py\", line 615, in _process_events\n event.tick(self._last_tick, remove)\nFile \"/usr/lib/python3.4/site-packages/kivy/clock.py\", line 353, in tick\n callback = self.get_callback()\nFile \"/usr/lib/python3.4/site-packages/kivy/clock.py\", line 320, in get_callback\n return callback()\nFile \"/usr/lib/python3.4/site-packages/kivy/weakmethod.py\", line 47, in __call__\n return getattr(self.proxy, self.method_name)\nAttributeError: 'Sandbox' object has no attribute '_f2'\n```\n\n", "before_files": [{"content": "'''\nSandbox\n=======\n\n.. versionadded:: 1.8.0\n\n.. warning::\n\n    This is experimental and subject to change as long as this warning notice\n    is present.\n\nThis is a widget that runs itself and all of its children in a Sandbox. That\nmeans if a child raises an Exception, it will be caught. The Sandbox\nitself runs its own Clock, Cache, etc.\n\nThe SandBox widget is still experimental and required for the Kivy designer.\nWhen the user designs their own widget, if they do something wrong (wrong size\nvalue, invalid python code), it will be caught correctly without breaking\nthe whole application. Because it has been designed that way, we are still\nenhancing this widget and the :mod:`kivy.context` module.\nDon't use it unless you know what you are doing.\n\n'''\n\n__all__ = ('Sandbox', )\n\nfrom kivy.context import Context\nfrom kivy.base import ExceptionManagerBase\nfrom kivy.clock import Clock\nfrom kivy.uix.widget import Widget\nfrom kivy.uix.floatlayout import FloatLayout\nfrom kivy.uix.relativelayout import RelativeLayout\nfrom kivy.lang import Builder\n\n\ndef sandbox(f):\n    def _f2(self, *args, **kwargs):\n        ret = None\n        with self:\n            ret = f(self, *args, **kwargs)\n        return ret\n    return _f2\n\n\nclass SandboxExceptionManager(ExceptionManagerBase):\n\n    def __init__(self, sandbox):\n        ExceptionManagerBase.__init__(self)\n        self.sandbox = sandbox\n\n    def handle_exception(self, e):\n        if not self.sandbox.on_exception(e):\n            return ExceptionManagerBase.RAISE\n        return ExceptionManagerBase.PASS\n\n\nclass SandboxContent(RelativeLayout):\n    pass\n\n\nclass Sandbox(FloatLayout):\n    '''Sandbox widget, used to trap all the exceptions raised by child\n    widgets.\n    '''\n\n    def __init__(self, **kwargs):\n        self._context = Context(init=True)\n        self._context['ExceptionManager'] = SandboxExceptionManager(self)\n        self._context.sandbox = self\n        self._context.push()\n        self.on_context_created()\n        self._container = None\n        super(Sandbox, self).__init__(**kwargs)\n        self._container = SandboxContent(size=self.size, pos=self.pos)\n        super(Sandbox, self).add_widget(self._container)\n        self._context.pop()\n\n        # force SandboxClock's scheduling\n        Clock.schedule_interval(self._clock_sandbox, 0)\n        Clock.schedule_once(self._clock_sandbox_draw, -1)\n        self.main_clock = object.__getattribute__(Clock, '_obj')\n\n    def __enter__(self):\n        self._context.push()\n\n    def __exit__(self, _type, value, traceback):\n        self._context.pop()\n        if _type is not None:\n            return self.on_exception(value, _traceback=traceback)\n\n    def on_context_created(self):\n        '''Override this method in order to load your kv file or do anything\n        else with the newly created context.\n        '''\n        pass\n\n    def on_exception(self, exception, _traceback=None):\n        '''Override this method in order to catch all the exceptions from\n        children.\n\n        If you return True, it will not reraise the exception.\n        If you return False, the exception will be raised to the parent.\n        '''\n        import traceback\n        traceback.print_tb(_traceback)\n        return True\n\n    on_touch_down = sandbox(Widget.on_touch_down)\n    on_touch_move = sandbox(Widget.on_touch_move)\n    on_touch_up = sandbox(Widget.on_touch_up)\n\n    @sandbox\n    def add_widget(self, *args, **kwargs):\n        self._container.add_widget(*args, **kwargs)\n\n    @sandbox\n    def remove_widget(self, *args, **kwargs):\n        self._container.remove_widget(*args, **kwargs)\n\n    @sandbox\n    def clear_widgets(self, *args, **kwargs):\n        self._container.clear_widgets()\n\n    @sandbox\n    def on_size(self, *args):\n        if self._container:\n            self._container.size = self.size\n\n    @sandbox\n    def on_pos(self, *args):\n        if self._container:\n            self._container.pos = self.pos\n\n    @sandbox\n    def _clock_sandbox(self, dt):\n        #import pdb; pdb.set_trace()\n        Clock.tick()\n        Builder.sync()\n\n    @sandbox\n    def _clock_sandbox_draw(self, dt):\n        Clock.tick_draw()\n        Builder.sync()\n        self.main_clock.schedule_once(self._call_draw, 0)\n\n    def _call_draw(self, dt):\n        self.main_clock.schedule_once(self._clock_sandbox_draw, -1)\n\nif __name__ == '__main__':\n    from kivy.base import runTouchApp\n    from kivy.uix.button import Button\n\n    class TestButton(Button):\n\n        def on_touch_up(self, touch):\n            #raise Exception('fdfdfdfdfdfdfd')\n            return super(TestButton, self).on_touch_up(touch)\n\n        def on_touch_down(self, touch):\n            #raise Exception('')\n            return super(TestButton, self).on_touch_down(touch)\n\n    s = Sandbox()\n    with s:\n        Builder.load_string('''\n<TestButton>:\n    canvas:\n        Color:\n            rgb: (.3, .2, 0) if self.state == 'normal' else (.7, .7, 0)\n        Rectangle:\n            pos: self.pos\n            size: self.size\n        Color:\n            rgb: 1, 1, 1\n        Rectangle:\n            size: self.texture_size\n            pos: self.center_x - self.texture_size[0] / 2.,\\\n                 self.center_y - self.texture_size[1] / 2.\n            texture: self.texture\n\n    # invalid... for testing.\n    #on_touch_up: root.d()\n    #on_touch_down: root.f()\n    on_release: root.args()\n    #on_press: root.args()\n''')\n        b = TestButton(text='Hello World')\n        s.add_widget(b)\n\n        # this exception is within the \"with\" block, but will be ignored by\n        # default because the sandbox on_exception will return True\n        raise Exception('hello')\n\n    runTouchApp(s)\n", "path": "kivy/uix/sandbox.py"}], "after_files": [{"content": "'''\nSandbox\n=======\n\n.. versionadded:: 1.8.0\n\n.. warning::\n\n    This is experimental and subject to change as long as this warning notice\n    is present.\n\nThis is a widget that runs itself and all of its children in a Sandbox. That\nmeans if a child raises an Exception, it will be caught. The Sandbox\nitself runs its own Clock, Cache, etc.\n\nThe SandBox widget is still experimental and required for the Kivy designer.\nWhen the user designs their own widget, if they do something wrong (wrong size\nvalue, invalid python code), it will be caught correctly without breaking\nthe whole application. Because it has been designed that way, we are still\nenhancing this widget and the :mod:`kivy.context` module.\nDon't use it unless you know what you are doing.\n\n'''\n\n__all__ = ('Sandbox', )\n\nfrom functools import wraps\nfrom kivy.context import Context\nfrom kivy.base import ExceptionManagerBase\nfrom kivy.clock import Clock\nfrom kivy.uix.widget import Widget\nfrom kivy.uix.floatlayout import FloatLayout\nfrom kivy.uix.relativelayout import RelativeLayout\nfrom kivy.lang import Builder\n\n\ndef sandbox(f):\n    @wraps(f)\n    def _f2(self, *args, **kwargs):\n        ret = None\n        with self:\n            ret = f(self, *args, **kwargs)\n        return ret\n    return _f2\n\n\nclass SandboxExceptionManager(ExceptionManagerBase):\n\n    def __init__(self, sandbox):\n        ExceptionManagerBase.__init__(self)\n        self.sandbox = sandbox\n\n    def handle_exception(self, e):\n        if not self.sandbox.on_exception(e):\n            return ExceptionManagerBase.RAISE\n        return ExceptionManagerBase.PASS\n\n\nclass SandboxContent(RelativeLayout):\n    pass\n\n\nclass Sandbox(FloatLayout):\n    '''Sandbox widget, used to trap all the exceptions raised by child\n    widgets.\n    '''\n\n    def __init__(self, **kwargs):\n        self._context = Context(init=True)\n        self._context['ExceptionManager'] = SandboxExceptionManager(self)\n        self._context.sandbox = self\n        self._context.push()\n        self.on_context_created()\n        self._container = None\n        super(Sandbox, self).__init__(**kwargs)\n        self._container = SandboxContent(size=self.size, pos=self.pos)\n        super(Sandbox, self).add_widget(self._container)\n        self._context.pop()\n\n        # force SandboxClock's scheduling\n        Clock.schedule_interval(self._clock_sandbox, 0)\n        Clock.schedule_once(self._clock_sandbox_draw, -1)\n        self.main_clock = object.__getattribute__(Clock, '_obj')\n\n    def __enter__(self):\n        self._context.push()\n\n    def __exit__(self, _type, value, traceback):\n        self._context.pop()\n        if _type is not None:\n            return self.on_exception(value, _traceback=traceback)\n\n    def on_context_created(self):\n        '''Override this method in order to load your kv file or do anything\n        else with the newly created context.\n        '''\n        pass\n\n    def on_exception(self, exception, _traceback=None):\n        '''Override this method in order to catch all the exceptions from\n        children.\n\n        If you return True, it will not reraise the exception.\n        If you return False, the exception will be raised to the parent.\n        '''\n        import traceback\n        traceback.print_tb(_traceback)\n        return True\n\n    on_touch_down = sandbox(Widget.on_touch_down)\n    on_touch_move = sandbox(Widget.on_touch_move)\n    on_touch_up = sandbox(Widget.on_touch_up)\n\n    @sandbox\n    def add_widget(self, *args, **kwargs):\n        self._container.add_widget(*args, **kwargs)\n\n    @sandbox\n    def remove_widget(self, *args, **kwargs):\n        self._container.remove_widget(*args, **kwargs)\n\n    @sandbox\n    def clear_widgets(self, *args, **kwargs):\n        self._container.clear_widgets()\n\n    @sandbox\n    def on_size(self, *args):\n        if self._container:\n            self._container.size = self.size\n\n    @sandbox\n    def on_pos(self, *args):\n        if self._container:\n            self._container.pos = self.pos\n\n    @sandbox\n    def _clock_sandbox(self, dt):\n        #import pdb; pdb.set_trace()\n        Clock.tick()\n        Builder.sync()\n\n    @sandbox\n    def _clock_sandbox_draw(self, dt):\n        Clock.tick_draw()\n        Builder.sync()\n        self.main_clock.schedule_once(self._call_draw, 0)\n\n    def _call_draw(self, dt):\n        self.main_clock.schedule_once(self._clock_sandbox_draw, -1)\n\nif __name__ == '__main__':\n    from kivy.base import runTouchApp\n    from kivy.uix.button import Button\n\n    class TestButton(Button):\n\n        def on_touch_up(self, touch):\n            #raise Exception('fdfdfdfdfdfdfd')\n            return super(TestButton, self).on_touch_up(touch)\n\n        def on_touch_down(self, touch):\n            #raise Exception('')\n            return super(TestButton, self).on_touch_down(touch)\n\n    s = Sandbox()\n    with s:\n        Builder.load_string('''\n<TestButton>:\n    canvas:\n        Color:\n            rgb: (.3, .2, 0) if self.state == 'normal' else (.7, .7, 0)\n        Rectangle:\n            pos: self.pos\n            size: self.size\n        Color:\n            rgb: 1, 1, 1\n        Rectangle:\n            size: self.texture_size\n            pos: self.center_x - self.texture_size[0] / 2.,\\\n                 self.center_y - self.texture_size[1] / 2.\n            texture: self.texture\n\n    # invalid... for testing.\n    #on_touch_up: root.d()\n    #on_touch_down: root.f()\n    on_release: root.args()\n    #on_press: root.args()\n''')\n        b = TestButton(text='Hello World')\n        s.add_widget(b)\n\n        # this exception is within the \"with\" block, but will be ignored by\n        # default because the sandbox on_exception will return True\n        raise Exception('hello')\n\n    runTouchApp(s)\n", "path": "kivy/uix/sandbox.py"}]}