input: Write a python function to calculate the area of a triangle given the lengths of its three sides using Heron's formula.
  assert math.isclose(calculate_area(3, 4, 5), 6.0)
  assert math.isclose(calculate_area(6, 8, 10), 24.0)
  assert math.isclose(calculate_area(7, 24, 25), 84.0)
output: import math
  
  def calculate_area(a, b, c):
      s = (a + b + c) / 2
      area = math.sqrt(s * (s - a) * (s - b) * (s - c))
      return area