input: Write a function to create a dictionary from a list of numbers where each key is a number from the list and its corresponding value is the square of that number. If the input list is empty, return an empty dictionary.
  
  
  def create_square_dict(numbers):
      return {num: num**2 for num in numbers}
  
  assert create_square_dict([1, 2, 3, 4, 5]) == {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
  assert create_square_dict([]) == {}
  
output: def create_square_dict(numbers):
      return {num: num**2 for num in numbers}