input: Write a function to create a dictionary where each key is a number from 1 to n and its corresponding value is the square of that number.
  assert build_square_dict(10) == {1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81, 10: 100}
output: def build_square_dict(n):
      return {i: i**2 for i in range(1, n+1)}