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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 get_end_time(self):
 """Get observation end time from file metadata."""

        mda_dict = self.filehandle.attributes()
        core_mda = mda_dict['coremetadata']
        end_time_str = self.parse_metadata_string(core_mda)
        self._end_time = datetime.strptime(end_time_str, "%Y-%m-%dT%H:%M:%SZ")