@property<EOL><INDENT>def reference_id(self):<DEDENT>
return self._reference_id<EOL>
Gets the reference_id of this ChargeRequest.
An optional ID you can associate with the transaction for your own purposes (such as to associate the transaction with an entity ID in your own database).  This value cannot exceed 40 characters.

:return: The reference_id of this ChargeRequest.
:rtype: str