<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def remove(self, key):
 """ Remove the data stored for the given key. Args: key (str):
 Key of the data to remove. Note: The container has to be opened in advance. """

        self.raise_error_if_not_open()

        if key in self._file:
            del self._file[key]