def get_session_not_on_or_after(self):
not_on_or_after = None<EOL>authn_statement_nodes = self.__query_assertion('<STR_LIT>')<EOL>if authn_statement_nodes:<EOL><INDENT>not_on_or_after = OneLogin_Saml2_Utils.parse_SAML_to_time(authn_statement_nodes[<NUM_LIT:0>].get('<STR_LIT>'))<EOL><DEDENT>return not_on_or_after<EOL>
Gets the SessionNotOnOrAfter from the AuthnStatement
Could be used to set the local session expiration

:returns: The SessionNotOnOrAfter value
:rtype: time|None