input: 
  def determine_commission_rate(gross_sales: float) -> float:
      """Determine the commission rate based on the gross sales amount.
      >>> determine_commission_rate(12000)
      0.1
      >>> determine_commission_rate(7500)
      0.07
      >>> determine_commission_rate(4000)
      0.05
      """
  
output:     if gross_sales >= 10000:
          return 0.1
      elif gross_sales >= 5000:
          return 0.07
      else:
          return 0.05