nodes: 0, module; 1, function_definition; 2, function_name:to_json; 3, parameters; 4, block; 5, identifier:self; 6, default_parameter; 7, default_parameter; 8, default_parameter; 9, default_parameter; 10, expression_statement; 11, return_statement; 12, identifier:drop_null; 13, True; 14, identifier:camel; 15, False; 16, identifier:indent; 17, None; 18, identifier:sort_keys; 19, False; 20, comment:"""Serialize self as JSON
  
          Args:
              drop_null: bool, default True. Remove 'empty' attributes. See
                  to_dict.
              camel: bool, default True. Convert keys to camelCase.
              indent: int, default None. See json built-in.
              sort_keys: bool, default False. See json built-in.
  
          Return:
              str: object params.
          """; 21, call; 22, attribute; 23, argument_list; 24, identifier:json; 25, identifier:dumps; 26, call; 27, keyword_argument; 28, keyword_argument; 29, attribute; 30, argument_list; 31, identifier:indent; 32, identifier:indent; 33, identifier:sort_keys; 34, identifier:sort_keys; 35, identifier:self; 36, identifier:to_dict; 37, identifier:drop_null; 38, identifier:camel
code: def to_json(self, drop_null=True, camel=False, indent=None, sort_keys=False):
          """Serialize self as JSON
  
          Args:
              drop_null: bool, default True. Remove 'empty' attributes. See
                  to_dict.
              camel: bool, default True. Convert keys to camelCase.
              indent: int, default None. See json built-in.
              sort_keys: bool, default False. See json built-in.
  
          Return:
              str: object params.
          """
          return json.dumps(self.to_dict(drop_null, camel), indent=indent,
                            sort_keys=sort_keys)