use "functional"

def testFunctionalChain() {
  data = [1,2,3,4,5,6,7]
  result = chain(data,
    ::filter, def(x) = x <= 4,
    ::sortby, def(x) = -x,
    ::map,    def(x) = x * 2,
  )
  assertEquals([8,6,4,2], result)
}