We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
`cupy.array_split` doesn't accept empty indecies
```
>>> x=cupy.array([1])
>>> cupy.array_split(x, [])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/unno/git/chainer/cupy/manipulation/split.py", line 32, in array_split
    ret.append(ary[skip + (slice(index, size),)])
UnboundLocalError: local variable 'index' referenced before assignment
```


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `cupy/manipulation/split.py`
Content:
```
1 import numpy
2 import six
3 
4 
5 def array_split(ary, indices_or_sections, axis=0):
6     """Splits an array into multiple sub arrays along a given axis.
7 
8     This function is almost equivalent to :func:`cupy.split`. The only
9     difference is that this function allows an integer sections that does not
10     evenly divide the axis.
11 
12     .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.array_split`
13 
14     """
15     if ary.ndim <= axis:
16         raise IndexError('Axis exceeds ndim')
17     size = ary.shape[axis]
18 
19     if numpy.isscalar(indices_or_sections):
20         each_size = (size - 1) // indices_or_sections + 1
21         indices = [i * each_size
22                    for i in six.moves.range(1, indices_or_sections)]
23     else:
24         indices = indices_or_sections
25 
26     skip = (slice(None),) * axis
27     ret = []
28     i = 0
29     for index in indices:
30         ret.append(ary[skip + (slice(i, index),)])
31         i = index
32     ret.append(ary[skip + (slice(index, size),)])
33 
34     return ret
35 
36 
37 def dsplit(ary, indices_or_sections):
38     """Splits an array into multiple sub arrays along the third axis.
39 
40     This is equivalent to ``split`` with ``axis=2``.
41 
42     .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`
43 
44     """
45     if ary.ndim <= 2:
46         raise ValueError('Cannot dsplit an array with less than 3 dimensions')
47     return split(ary, indices_or_sections, 2)
48 
49 
50 def hsplit(ary, indices_or_sections):
51     """Splits an array into multiple sub arrays horizontally.
52 
53     This is equivalent to ``split`` with ``axis=0`` if ``ary`` has one
54     dimension, and otherwise that with ``axis=1``.
55 
56     .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.hsplit`
57 
58     """
59     if ary.ndim == 0:
60         raise ValueError('Cannot hsplit a zero-dimensional array')
61     if ary.ndim == 1:
62         return split(ary, indices_or_sections, 0)
63     else:
64         return split(ary, indices_or_sections, 1)
65 
66 
67 def split(ary, indices_or_sections, axis=0):
68     """Splits an array into multiple sub arrays along a given axis.
69 
70     Args:
71         ary (cupy.ndarray): Array to split.
72         indices_or_sections (int or sequence of ints): A value indicating how
73             to divide the axis. If it is an integer, then is treated as the
74             number of sections, and the axis is evenly divided. Otherwise,
75             the integers indicate indices to split at. Note that the sequence
76             on the device memory is not allowed.
77         axis (int): Axis along which the array is split.
78 
79     Returns:
80         A list of sub arrays. Eacy array is a view of the corresponding input
81         array.
82 
83     .. seealso:: :func:`numpy.split`
84 
85     """
86     if ary.ndim <= axis:
87         raise IndexError('Axis exceeds ndim')
88     size = ary.shape[axis]
89 
90     if numpy.isscalar(indices_or_sections):
91         if size % indices_or_sections != 0:
92             raise ValueError(
93                 'indices_or_sections must divide the size along the axes.\n'
94                 'If you want to split the array into non-equally-sized '
95                 'arrays, use array_split instead.')
96     return array_split(ary, indices_or_sections, axis)
97 
98 
99 def vsplit(ary, indices_or_sections):
100     """Splits an array into multiple sub arrays along the first axis.
101 
102     This is equivalent to ``split`` with ``axis=0``.
103 
104     .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`
105 
106     """
107     if ary.ndim <= 1:
108         raise ValueError('Cannot vsplit an array with less than 2 dimensions')
109     return split(ary, indices_or_sections, 0)
110
```
--- 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/cupy/manipulation/split.py b/cupy/manipulation/split.py
--- a/cupy/manipulation/split.py
+++ b/cupy/manipulation/split.py
@@ -23,6 +23,9 @@
     else:
         indices = indices_or_sections
 
+    if len(indices) == 0:
+        return [ary]
+
     skip = (slice(None),) * axis
     ret = []
     i = 0

{"golden_diff": "diff --git a/cupy/manipulation/split.py b/cupy/manipulation/split.py\n--- a/cupy/manipulation/split.py\n+++ b/cupy/manipulation/split.py\n@@ -23,6 +23,9 @@\n     else:\n         indices = indices_or_sections\n \n+    if len(indices) == 0:\n+        return [ary]\n+\n     skip = (slice(None),) * axis\n     ret = []\n     i = 0\n", "issue": "`cupy.array_split` doesn't accept empty indecies\n```\n>>> x=cupy.array([1])\n>>> cupy.array_split(x, [])\nTraceback (most recent call last):\n  File \"<stdin>\", line 1, in <module>\n  File \"/home/unno/git/chainer/cupy/manipulation/split.py\", line 32, in array_split\n    ret.append(ary[skip + (slice(index, size),)])\nUnboundLocalError: local variable 'index' referenced before assignment\n```\n\n", "before_files": [{"content": "import numpy\nimport six\n\n\ndef array_split(ary, indices_or_sections, axis=0):\n    \"\"\"Splits an array into multiple sub arrays along a given axis.\n\n    This function is almost equivalent to :func:`cupy.split`. The only\n    difference is that this function allows an integer sections that does not\n    evenly divide the axis.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.array_split`\n\n    \"\"\"\n    if ary.ndim <= axis:\n        raise IndexError('Axis exceeds ndim')\n    size = ary.shape[axis]\n\n    if numpy.isscalar(indices_or_sections):\n        each_size = (size - 1) // indices_or_sections + 1\n        indices = [i * each_size\n                   for i in six.moves.range(1, indices_or_sections)]\n    else:\n        indices = indices_or_sections\n\n    skip = (slice(None),) * axis\n    ret = []\n    i = 0\n    for index in indices:\n        ret.append(ary[skip + (slice(i, index),)])\n        i = index\n    ret.append(ary[skip + (slice(index, size),)])\n\n    return ret\n\n\ndef dsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays along the third axis.\n\n    This is equivalent to ``split`` with ``axis=2``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`\n\n    \"\"\"\n    if ary.ndim <= 2:\n        raise ValueError('Cannot dsplit an array with less than 3 dimensions')\n    return split(ary, indices_or_sections, 2)\n\n\ndef hsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays horizontally.\n\n    This is equivalent to ``split`` with ``axis=0`` if ``ary`` has one\n    dimension, and otherwise that with ``axis=1``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.hsplit`\n\n    \"\"\"\n    if ary.ndim == 0:\n        raise ValueError('Cannot hsplit a zero-dimensional array')\n    if ary.ndim == 1:\n        return split(ary, indices_or_sections, 0)\n    else:\n        return split(ary, indices_or_sections, 1)\n\n\ndef split(ary, indices_or_sections, axis=0):\n    \"\"\"Splits an array into multiple sub arrays along a given axis.\n\n    Args:\n        ary (cupy.ndarray): Array to split.\n        indices_or_sections (int or sequence of ints): A value indicating how\n            to divide the axis. If it is an integer, then is treated as the\n            number of sections, and the axis is evenly divided. Otherwise,\n            the integers indicate indices to split at. Note that the sequence\n            on the device memory is not allowed.\n        axis (int): Axis along which the array is split.\n\n    Returns:\n        A list of sub arrays. Eacy array is a view of the corresponding input\n        array.\n\n    .. seealso:: :func:`numpy.split`\n\n    \"\"\"\n    if ary.ndim <= axis:\n        raise IndexError('Axis exceeds ndim')\n    size = ary.shape[axis]\n\n    if numpy.isscalar(indices_or_sections):\n        if size % indices_or_sections != 0:\n            raise ValueError(\n                'indices_or_sections must divide the size along the axes.\\n'\n                'If you want to split the array into non-equally-sized '\n                'arrays, use array_split instead.')\n    return array_split(ary, indices_or_sections, axis)\n\n\ndef vsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays along the first axis.\n\n    This is equivalent to ``split`` with ``axis=0``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`\n\n    \"\"\"\n    if ary.ndim <= 1:\n        raise ValueError('Cannot vsplit an array with less than 2 dimensions')\n    return split(ary, indices_or_sections, 0)\n", "path": "cupy/manipulation/split.py"}], "after_files": [{"content": "import numpy\nimport six\n\n\ndef array_split(ary, indices_or_sections, axis=0):\n    \"\"\"Splits an array into multiple sub arrays along a given axis.\n\n    This function is almost equivalent to :func:`cupy.split`. The only\n    difference is that this function allows an integer sections that does not\n    evenly divide the axis.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.array_split`\n\n    \"\"\"\n    if ary.ndim <= axis:\n        raise IndexError('Axis exceeds ndim')\n    size = ary.shape[axis]\n\n    if numpy.isscalar(indices_or_sections):\n        each_size = (size - 1) // indices_or_sections + 1\n        indices = [i * each_size\n                   for i in six.moves.range(1, indices_or_sections)]\n    else:\n        indices = indices_or_sections\n\n    if len(indices) == 0:\n        return [ary]\n\n    skip = (slice(None),) * axis\n    ret = []\n    i = 0\n    for index in indices:\n        ret.append(ary[skip + (slice(i, index),)])\n        i = index\n    ret.append(ary[skip + (slice(index, size),)])\n\n    return ret\n\n\ndef dsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays along the third axis.\n\n    This is equivalent to ``split`` with ``axis=2``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`\n\n    \"\"\"\n    if ary.ndim <= 2:\n        raise ValueError('Cannot dsplit an array with less than 3 dimensions')\n    return split(ary, indices_or_sections, 2)\n\n\ndef hsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays horizontally.\n\n    This is equivalent to ``split`` with ``axis=0`` if ``ary`` has one\n    dimension, and otherwise that with ``axis=1``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.hsplit`\n\n    \"\"\"\n    if ary.ndim == 0:\n        raise ValueError('Cannot hsplit a zero-dimensional array')\n    if ary.ndim == 1:\n        return split(ary, indices_or_sections, 0)\n    else:\n        return split(ary, indices_or_sections, 1)\n\n\ndef split(ary, indices_or_sections, axis=0):\n    \"\"\"Splits an array into multiple sub arrays along a given axis.\n\n    Args:\n        ary (cupy.ndarray): Array to split.\n        indices_or_sections (int or sequence of ints): A value indicating how\n            to divide the axis. If it is an integer, then is treated as the\n            number of sections, and the axis is evenly divided. Otherwise,\n            the integers indicate indices to split at. Note that the sequence\n            on the device memory is not allowed.\n        axis (int): Axis along which the array is split.\n\n    Returns:\n        A list of sub arrays. Eacy array is a view of the corresponding input\n        array.\n\n    .. seealso:: :func:`numpy.split`\n\n    \"\"\"\n    if ary.ndim <= axis:\n        raise IndexError('Axis exceeds ndim')\n    size = ary.shape[axis]\n\n    if numpy.isscalar(indices_or_sections):\n        if size % indices_or_sections != 0:\n            raise ValueError(\n                'indices_or_sections must divide the size along the axes.\\n'\n                'If you want to split the array into non-equally-sized '\n                'arrays, use array_split instead.')\n    return array_split(ary, indices_or_sections, axis)\n\n\ndef vsplit(ary, indices_or_sections):\n    \"\"\"Splits an array into multiple sub arrays along the first axis.\n\n    This is equivalent to ``split`` with ``axis=0``.\n\n    .. seealso:: :func:`cupy.split` for more detail, :func:`numpy.dsplit`\n\n    \"\"\"\n    if ary.ndim <= 1:\n        raise ValueError('Cannot vsplit an array with less than 2 dimensions')\n    return split(ary, indices_or_sections, 0)\n", "path": "cupy/manipulation/split.py"}]}