code: def add_location(self, location_name, parent_name=None, er_data=None, pmag_data=None):
          
          if not location_name:
              return False
          location = Location(location_name, data_model=self.data_model, er_data=er_data, pmag_data=pmag_data)
          self.locations.append(location)
          return location
docs: Create a Location object and add it to self.locations.