input: Write a python function to create a dictionary from a list with list elements as keys and their squares as values.
  assert create_dict([1, 2, 3, 4]) == {1: 1, 2: 4, 3: 9, 4: 16}
  assert create_dict([5, 6, 7, 8]) == {5: 25, 6: 36, 7: 49, 8: 64}
  assert create_dict([9, 10]) == {9: 81, 10: 100}
output: def create_dict(lst):
      return {x: x**2 for x in lst}