input: Write a function to create a Python function that takes in a list and prints a dictionary with the elements and the product of each element. The function should return the dictionary.
  assert product_of_list([2, 3, 4])=={2: 4, 3: 9, 4: 16}
  assert product_of_list([0, 1, 2, 3])=={0: 0, 1: 1, 2: 4, 3: 9}
  assert product_of_list([])=={}
  assert product_of_list([10])=={10: 100}
  assert product_of_list([5, 5, 5])=={5: 25}
output: def product_of_list(lst):
      return {x: x * x for x in lst}