func (c *raftMembershipClient) Join(ctx context.Context, in *JoinRequest, opts ...grpc.CallOption) (*JoinResponse, error) {
    out := new(JoinResponse)
    err := c.cc.Invoke(ctx, "/docker.swarmkit.v1.RaftMembership/Join", in, out, opts...)
    if err != nil {
        return nil, err