input: Write a python function to calculate the average height from a list of heights.
  assert average_height([1.78, 1.90, 1.75, 1.82]) == 1.8125
  assert average_height([1.60, 1.65, 1.70, 1.75, 1.80]) == 1.70
  assert average_height([1.50, 1.55, 1.60]) == 1.55
output: def average_height(heights):
      return sum(heights) / len(heights)