def clear_source(self):
<EOL>if (self.get_source_metadata().is_read_only() or<EOL>self.get_source_metadata().is_required()):<EOL><INDENT>raise errors.NoAccess()<EOL><DEDENT>self._my_map['<STR_LIT>'] = self._source_default<EOL>
Removes the source.

        raise:  NoAccess - ``Metadata.isRequired()`` is ``true`` or
                ``Metadata.isReadOnly()`` is ``true``
        *compliance: mandatory -- This method must be implemented.*