input: Write a function to make the following Python code snippet more efficient. The function should return the commission rate based on the gross sales amount. 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.
  
  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(15000) == 0.1
  assert determine_commission_rate(7500) == 0.07
  assert determine_commission_rate(3000) == 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