@reference_id.setter<EOL><INDENT>def reference_id(self, reference_id):<DEDENT>
if reference_id is None:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>if len(reference_id) > <NUM_LIT>:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>self._reference_id = reference_id<EOL>
Sets 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.

:param reference_id: The reference_id of this ChargeRequest.
:type: str