any given instance string

def literal(compiler, cont, arg):
  '''any given instance string'''
  text = compiler.new_var(il.ConstLocalVar('text'))
  pos = compiler.new_var(il.ConstLocalVar('pos'))
  p = compiler.new_var(il.LocalVar('p'))
  i = compiler.new_var(il.LocalVar('i'))
  x = compiler.new_var(il.ConstLocalVar('x'))
  length = compiler.new_var(il.ConstLocalVar('length'))  
  length2 = compiler.new_var(il.ConstLocalVar('length2'))  
  if isinstance(arg, Var):
    return il.Begin((
      il.Assign(x, il.Deref(arg)),
      il.AssignFromList(text, pos, il.parse_state),
      il.Assign(length, il.Len(text)),
      il.Assign(length, il.Len(x)),
      il.Assign(i, il.Integer(0)),
      il.Assign(p, pos),
      il.while_(il.and_(il.Lt(i, length2), il.Lt(p, length), il.Eq(il.GetItem(text, p), il.GetItem(x, i))), 
        il.AddAssign(p, il.Integer(1))),
      il.If(il.Lt(i, length2), 
        il.failcont(il.NONE),
        il.begin(il.append_failcont(compiler, 
          il.SetParseState(il.Tuple(text, pos))),
          il.SetParseState(il.Tuple(text, p)),
          cont(arg)))))
  elif isinstance(arg, String):
    arg = arg.interlang()
    return il.Begin((
      il.AssignFromList(text, pos, il.parse_state),
      il.Assign(length, il.Len(text)),
      il.Assign(length2, il.Len(arg)),
      il.Assign(i, il.Integer(0)),
      il.Assign(p, pos),
      il.while_(il.and_(il.Lt(i, length2), il.Lt(p, length), il.Eq(il.GetItem(text, p), il.GetItem(arg, i))), 
        il.AddAssign(p, il.Integer(1)),
        il.AddAssign(i, il.Integer(1)),
        ),
      il.If(il.Lt(i, length2), 
        il.failcont(il.NONE),
        il.begin(il.append_failcont(compiler, 
          il.SetParseState(il.Tuple(text, pos))),
          il.SetParseState(il.Tuple(text, p)),
          cont(arg)))))
  else:
    raise CompileTypeError