input: Write a function to optimize the determination of the commission rate based on the gross sales. If the gross sales are greater than or equal to 10000, the commission rate should be 0.1. If the gross sales are between 5000 and 9999, the commission rate should be 0.07. If the gross sales are less than 5000, the commission rate should be 0.05. The function should return the commission rate.
  def determine_commission_rate(gross_sales):
      if gross_sales >= 10000:
          return 0.1
      elif gross_sales >= 5000:
          return 0.07
      else:
          return 0.05
  assert determine_commission_rate(12000)==0.1
  assert determine_commission_rate(7500)==0.07
  assert determine_commission_rate(4000)==0.05
output: def determine_commission_rate(gross_sales):
      if gross_sales >= 10000:
          return 0.1
      elif gross_sales >= 5000:
          return 0.07
      else:
          return 0.05