(self, planet_id)
return self._planets.get(planet_id)
:param int planet_id:
        :return: The planet associated with planet_id
        :rtype: entity.Planet
:param int planet_id:
        :return: The planet associated with planet_id
        :rtype: entity.Planet
: param int planet_id : : return : The planet associated with planet_id : rtype : entity . Planet
def get_planet(self, planet_id):
        """
        :param int planet_id:
        :return: The planet associated with planet_id
        :rtype: entity.Planet
        """
        return self._planets.get(planet_id)
def get_planet ( self , planet_id ) : return self . _planets . get ( planet_id )