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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _compute_metadata_from_readers(self):
 """Determine pieces of metadata from the readers loaded."""

        mda = {'sensor': self._get_sensor_names()}

        # overwrite the request start/end times with actual loaded data limits
        if self.readers:
            mda['start_time'] = min(x.start_time
                                    for x in self.readers.values())
            mda['end_time'] = max(x.end_time
                                  for x in self.readers.values())
        return mda