@property<EOL><INDENT>def _regex_strings(self):<DEDENT>
domain = <NUM_LIT:0><EOL>if domain not in self.domains:<EOL><INDENT>self.register_domain(domain=domain)<EOL><DEDENT>return self.domains[domain]._regex_strings<EOL>
A property to link into IntentEngine's _regex_strings.

Warning: this is only for backwards compatiblility and should not be used if you
    intend on using domains.

Returns: the domains _regex_strings from its IntentEngine