def add_collection(self, identifier_collection):
try:<EOL><INDENT>new_source_identifiers = identifier_collection.source_identifiers<EOL>self.source_identifiers.update(new_source_identifiers)<EOL><DEDENT>except AttributeError:<EOL><INDENT>msg = "<STR_LIT>"<EOL>raise AttributeError(msg)<EOL><DEDENT>
:type identifier_collection: a SimpleIdentifierCollection