Named input channel for a process in DSL2

[multimeric]

Say I have the following process in DSL2:

process protein_filter {
    input:
        tuple(
            path(seqs),
            val(metadata)
        )
        val(max)
    script:
        """
        seqkit seq --max-len ${max} ${seqs} > filtered.fa
        """
}

How can I assign a name to the input channels (a tuple channel and a value channel respectively), so that I can pipe into it using multiMap:

files |
  map {
    (it, [some: "metadata"])
  } |
  multiMap {
    tupleChannel: it
    value: 100_000
  }