input: Write a function to calculate BMI given height and weight.
  assert bmi_calculation(1.75, 70) == 22.857142857142858
  assert bmi_calculation(1.60, 50) == 19.53125
  assert bmi_calculation(1.80, 90) == 27.777777777777775
output: def bmi_calculation(height, weight):
      return weight / (height ** 2)