code: def has_connection(cls, pid, connection):
          
          with cls._lock:
              cls._ensure_pool_exists(pid)
              return connection in cls._pools[pid]
docs: Check to see if a pool has the specified connection
  
          :param str pid: The pool ID
          :param connection: The connection to check for
          :type connection: psycopg2.extensions.connection
          :rtype: bool