input: Write a function to generate a random 6-digit number. The function should return the generated number.
  import random
  
  def generate_six_digit_number():
      return random.randint(100000, 999999)
  assert generate_six_digit_number() >= 100000
  assert generate_six_digit_number() <= 999999
output: import random
  
  def generate_six_digit_number():
      return random.randint(100000, 999999)