code: def _get_client_from_cache(self, client_id):
          
          data = self._read_uaa_cache()
  
          # Only if we've cached any for this issuer
          if self.uri not in data:
              return
  
          for client in data[self.uri]:
              if client['id'] == client_id:
                  return client
docs: For the given client_id return what is
          cached.