def get_errors(self):
errors = []<EOL>errors.extend(self._get_signature_errors())<EOL>errors.extend(self._get_additional_errors())<EOL>errors.extend(self._get_entry_errors())<EOL>return errors if errors else None<EOL>
Verify that this MAR file is well formed.

        Returns:
            A list of strings describing errors in the MAR file
            None if this MAR file appears well formed.