def register_entity(self, entity_value, entity_type, alias_of=None, domain=<NUM_LIT:0>):
if domain not in self.domains:<EOL><INDENT>self.register_domain(domain=domain)<EOL><DEDENT>self.domains[domain].register_entity(entity_value=entity_value,<EOL>entity_type=entity_type,<EOL>alias_of=alias_of)<EOL>
Register an entity to be tagged in potential parse results.

Args:
    entity_value(str): the value/proper name of an entity instance
        (Ex: "The Big Bang Theory")
    entity_type(str): the type/tag of an entity instance (Ex: "Television Show")
    domain(str): a string representing the domain you wish to add the entity to