input: Write a python function to calculate the total cost given price and quantity.
  assert get_total_cost(5.00, 6) == 30.00
  assert get_total_cost(10.00, 3) == 30.00
  assert get_total_cost(7.50, 4) == 30.00
output: def get_total_cost(price, quantity):
      return price * quantity