human
Solve the following python programming problem given the following code:
def mock_open(mock = None, read_data = '') : 
    '
    A helper function to create a mock to replace the use of `open`. It works
    for `open` called directly or used as a context manager.

    The `mock` argument is the mock object to configure. If `None` (the
    default) then a `MagicMock` will be created for you, with the API limited
    to methods or attributes available on standard file handles.

    `read_data` is a string for the `read` methoddline`, and `readlines` of the
    file handle to return.  This is an empty string by default.
    ' 
    def _readlines_side_effect(* args, **kwargs) : 
        if (handle.readlines.return_value is not None) : 
            return handle.readlines.return_value 
return list (_state [0]) 
def _read_side_effect(* args, **kwargs) : 
        if (handle.read.return_value is not None) : 
            return handle.read.return_value 
return type (read_data) ().join (_state [0]) 
def _readline_side_effect() : 
        if (handle.readline.return_value is not None) : 
            while True : 
                (yield handle.readline.return_value) 
for line in _state [0] : 
            (yield line) 
global file_spec 
    if (file_spec is None) : 
        if six.PY3 : 
            import _io 
            file_spec = list (set (dir (_io.TextIOWrapper)).union (set (dir (_io.BytesIO)))) 
else : 
            file_spec = file 
if (mock is None) : 
        mock = MagicMock (name = 'open', spec = open) 
handle = MagicMock (spec = file_spec) 
    handle.__enter__.return_value = handle 
    _state = [_iterate_read_data (read_data), None] 
    handle.write.return_value = None 
    handle.read.return_value = None 
    handle.readline.return_value = None 
    handle.readlines.return_value = None 
    handle.read.side_effect = _read_side_effect 
    _state [1] = _readline_side_effect () 
    handle.readline.side_effect = _state [1] 
    handle.readlines.side_effect = _readlines_side_effect 
    def reset_data(* args, **kwargs) : 
        _state [0] = _iterate_read_data (read_data) 
     ...

    
    

    Fix the buggy line: mock.return_value = _read_side_effect
assistant
#Here is Python program to fix the buggy line: mock.

mock.return_value = handle