input: ### Instruction:
  Write a Python script that takes a list of integers and returns a list of tuples that contain the index and square of each number in the original list.
  
  ### Input:
  nums = [1, 2, 3, 4, 5]
  
  ### Output:
  def square_index(nums):
      return [(index, num ** 2) for index, num in enumerate(nums)]
  
  assert square_index([1, 2, 3, 4, 5])==[(0, 1), (1, 4), (2, 9), (3, 16), (4, 25)]
  assert square_index([0, -1, -2, 3])==[(0, 0), (1, 1), (2, 4), (3, 9)]
  assert square_index([])==[]
output:     return [(index, num ** 2) for index, num in enumerate(nums)]