input: Write a function to make the provided Python function more efficient by eliminating unnecessary conditional checks and directly returning the commission rate based on the gross sales value.
  
  ### Input:
  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
  
  ### 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
  
  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