input: Write a python function to sort a list of tuples by their first element.
  assert sortTuplesByFirstElement([(3, 'ape'), (1, 'cat'), (4, 'dog'), (2, 'bee')]) == [(1, 'cat'), (2, 'bee'), (3, 'ape'), (4, 'dog')]
  assert sortTuplesByFirstElement([(5, 'zebra'), (2, 'lion'), (3, 'tiger')]) == [(2, 'lion'), (3, 'tiger'), (5, 'zebra')]
  assert sortTuplesByFirstElement([(10, 'apple'), (7, 'banana'), (8, 'cherry')]) == [(7, 'banana'), (8, 'cherry'), (10, 'apple')]
output: def sortTuplesByFirstElement(tuples_list):
      return sorted(tuples_list, key=lambda x: x[0])