Calling something().toSeq() vs. toSeq(something()) Compile time error: Error: type mismatch: got ()

main.nim

template toSeq(iter: expr): expr {.immediate.} =
  var result = newSeq[type(iter)]()
  for x in iter: result.add(x)  
  result

iterator something: string =
  yield "Hello"
  yield "World"

var info = something().toSeq()

echo info[0]