code: def add_site_property(self, property_name, values):
          
          if len(values) != len(self.sites):
              raise ValueError("Values must be same length as sites.")
          for site, val in zip(self.sites, values):
              site.properties[property_name] = val
docs: Adds a property to a site.
  
          Args:
              property_name (str): The name of the property to add.
              values (list): A sequence of values. Must be same length as
                  number of sites.