def __init__(self, source_name=None, identifier=None,<EOL>identifier_collection=None):
self.source_identifiers = collections.OrderedDict()<EOL>self._primary_identifier = None<EOL>if identifier_collection:<EOL><INDENT>self.add_collection(identifier_collection=identifier_collection)<EOL><DEDENT>elif (source_name and identifier):<EOL><INDENT>self.add(source_name=source_name,<EOL>identifier=identifier)<EOL><DEDENT>
:type source_name: String
:type identifier: String or ?
:type identifier_collection:  subject_abcs.IdentifierCollection