input: Write a function to generate a random 6-digit number in Python. The function should return this number as an integer.
  assert generate_6_digit_number()==123456
  assert generate_6_digit_number()==654321
  assert generate_6_digit_number()==987654
output: import random
  
  def generate_6_digit_number():
      return random.randint(100000, 999999)