input: Write a function to optimize the given Python code snippet by reducing unnecessary comparisons. The function should determine the commission rate based on the gross sales amount. If gross_sales is greater than or equal to 10000, the commission rate should be 0.1. If gross_sales is between 5000 and 9999, the commission rate should be 0.07. If gross_sales is less than 5000, the commission rate should be 0.05. The function should directly return the commission rate without assigning it to a variable.
  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
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