code: def get(cls, pid, session):
          
          with cls._lock:
              cls._ensure_pool_exists(pid)
              return cls._pools[pid].get(session)
docs: Get an idle, unused connection from the pool. Once a connection has
          been retrieved, it will be marked as in-use until it is freed.
  
          :param str pid: The pool ID
          :param queries.Session session: The session to assign to the connection
          :rtype: psycopg2.extensions.connection