input: Write a function to make the following Python code snippet more efficient: 
  
  def determine_commission_rate(gross_sales):
      if gross_sales >= 10000:
          commission_rate = 0.1
      elif gross_sales >= 5000 and gross_sales < 10000:
          commission_rate = 0.07
      elif gross_sales < 5000:
          commission_rate = 0.05
      return commission_rate
  
  assert determine_commission_rate(12000)==0.1
  assert determine_commission_rate(7500)==0.07
  assert determine_commission_rate(4000)==0.05
  assert determine_commission_rate(10000)==0.1
  assert determine_commission_rate(5000)==0.07
  
  def determine_commission_rate(gross_sales):
      if gross_sales >= 10000:
          return 0.1
      elif gross_sales >= 5000:
          return 0.07
      else:
          return 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