input: Write a function to create a dictionary where each key is an element from the input list and the corresponding value is the product of that element with itself. The function should return the dictionary.
  assert product_of_list([7, 8, 5])=={7: 49, 8: 64, 5: 25}
  assert product_of_list([2, 3, 4])=={2: 4, 3: 9, 4: 16}
  assert product_of_list([])=={}
  assert product_of_list([0])=={0: 0}
  assert product_of_list([-1, -2, -3])=={-1: 1, -2: 4, -3: 9}
output: def product_of_list(lst):
      return {x: x * x for x in lst}