input: Write a python function to calculate the area of a triangle given its three sides.
  assert math.isclose(get_area(5, 6, 7), 14.696938456699069)
  assert math.isclose(get_area(3, 4, 5), 6.0)
  assert math.isclose(get_area(10, 10, 10), 43.30127018922193)
output: import math
  
  def get_area(a, b, c):
      s = (a + b + c) / 2
      area = math.sqrt(s * (s - a) * (s - b) * (s - c))
      return area