def weighted_blend(feat_a_pre, w_a_pre, re_feat_bp_pre):
    """
    Compute the l-1 th Recovered by weighted blend
    Params:
        feat_a_pre(torch.Tensor): l-1 layer feat_a F_A^[L-1]
        w_a_pre(torch.Tensor): W_A^[L-1]
        re_feat_bp_pre(torch.Tensor): R_BP^[L-1]
    Return:
        F_AP^[L-1]
    """
    return feat_a_pre*w_a_pre + re_feat_bp_pre*(1-w_a_pre)