gistfile1.txt

proc delete*[T](s: var seq[T], first, last: int) =
  ## Deletes in `s` the items at position `first` .. `last`. This modifies
  ## `s` itself, it does not return a copy.
  var i = first
  var j = last+1
  var newLen = len(s)-j+i
  while i < newLen:
    s[i].shallowCopy(s[j])
    inc(i)
    inc(j)
  setlen(s, newLen)

proc insert*[T](sOne: var seq[T], sTwo: var seq[T], pos: int) =
  ## Inserts items in `sTwo` into `sOne` at position `pos`. This modifies
  ## `sOne` itself, it does not return a copy.
  
  var j = len(sOne)
  var i = len(sOne)+len(sTwo)
  sOne.setLen(i)
  dec(j)
  dec(i)
  # Move items after `pos` to the end of the sequence.
  while j >= pos:
    sOne[i].shallowCopy(sOne[j])
    dec(i)
    dec(j)
  # Insert items from `sTwo` into `sOne` at `pos`
  j = pos
  for item in sTwo:
    sOne[j] = item
    inc(j)