input: Write a function to optimize a Python code snippet that calculates the commission rate based on gross sales. The function should directly return the commission rate to make it more efficient. If gross_sales is greater than or equal to 10000, return 0.1. If gross_sales is greater than or equal to 5000 and less than 10000, return 0.07. Otherwise, if gross_sales is less than 5000, return 0.05.
  
  assert determine_commission_rate(12000) == 0.1
  assert determine_commission_rate(7500) == 0.07
  assert determine_commission_rate(4500) == 0.05
  assert determine_commission_rate(5000) == 0.07
  assert determine_commission_rate(10000) == 0.1
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