code: def create_site(self, site, states=None):
          
          if site not in self.sites:
              self.sites.append(site)
          if states is not None:
              self.site_states.setdefault(site, [])
              try:
                  states = list(states)
              except TypeError:
                  return
              self.add_site_states(site, states)
docs: Create a new site on an agent if it doesn't already exist.