def connect(self, node, properties=None):
if len(self):<EOL><INDENT>raise AttemptedCardinalityViolation(<EOL>"<STR_LIT>".format(self))<EOL><DEDENT>else:<EOL><INDENT>return super(ZeroOrOne, self).connect(node, properties)<EOL><DEDENT>
Connect to a node.

:param node:
:type: StructuredNode
:param properties: relationship properties
:type: dict
:return: True / rel instance