input: Write a function to convert a list to a list of single-element tuples.
  assert listToTuple([1, 2, 3, 4, 5]) == [(1,), (2,), (3,), (4,), (5,)]
  assert listToTuple(['a', 'b', 'c']) == [('a',), ('b',), ('c',)]
  assert listToTuple([]) == []
output: def listToTuple(lst):
      return [(x,) for x in lst]