@identifiers.setter<EOL><INDENT>def identifiers(self, identifiers):<DEDENT>
if (isinstance(identifiers, subject_abcs.IdentifierCollection) or<EOL>identifiers is None):<EOL><INDENT>self._identifiers = identifiers<EOL><DEDENT>else:<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>
:type identifiers:  subject_abcs.IdentifierCollection