'If the mode is r+, return a L{_ReadFile} with the contents given to
this path\'s initializer.
@raise OSError: If the mode is unsupported.
@return: A L{_ReadFile} instance'

def open(self, mode):

    if (mode == 'rb+'):
        return _ReadFile(self.contents)
    raise OSError(ENOSYS, 'Function    not    implemented')
