How to convert Seq bool to UInt value in chisel?

Question

I want to convert Seq[Bool] into a UInt value. I try asUInt method, but it report an error that asUInt is not a member of IndexedSeq.

For example:

val valid = Wire(Vec(4, Bool()))
val ready = Wire(Vec(4, Bool()))
val fire = (x zip y).map{case (vld, rdy) => vld && rdy}
val fire_mask = fire.asUInt()