Flatty doesnt handle custom range arrays properly #32

import flatty

var 
  arr: array[-2..0, int]
  arr2: array[10..11, int]
for i, x in arr.pairs:
  arr[i] = i
for i, x in arr2.pairs:
  arr2[i] = i

assert arr2.toFlatty().fromFlatty(array[10..11, int]) == [10, 11] # Compile time error
assert arr.toFlatty().fromFlatty(array[-2..0, int]) == [-2, -1, 0] # Runtime bug

proc toFlatty*[T](s: var string, x: openarray[T]) =
  when T.supportsMemCopy:
    # Copy to
  else:
    for val in x:
      s.toFlatty(val)
  
proc toFlatty*[N, T](s: var string, x: array[N, T]) =
  s.toFlatty(x.toOpenArray(0, x.len - 1))
  
proc toFlatty*[T](s: var string, x: seq[T]) =
  if x.len > 0:
    s.toFlatty x.len
    s.toFlatty(x.toOpenArray(0, x.len - 1))