let find_call_input_nodes pdg_caller call_stmt in_key =
  match in_key with
    | PdgIndex.Signature.InCtrl
    | PdgIndex.Signature.InNum _ ->
        let idx = PdgTypes.Pdg.get_index pdg_caller in
        let _, call_sgn = FI.find_call idx call_stmt in
        let node = PdgIndex.Signature.find_in_info call_sgn in_key in
          [(node,None)], None
    | PdgIndex.Signature.InImpl zone ->
        let nodes, undef =
          find_location_nodes_at_stmt pdg_caller call_stmt ~before:true zone
        in nodes, undef