input: Write a function to take a list of integers and return a list of tuples where each tuple contains the index and the square of each number in the original list.
  square_index([1, 2, 3, 4, 5])
  # Output: [(0, 1), (1, 4), (2, 9), (3, 16), (4, 25)]
output: def square_index(lst):
      return [(i, x**2) for i, x in enumerate(lst)]