input: Write a function to generate a random 6-digit number in Python. The function should return the generated number as an integer.
  assert generate_random_number()==123456
  assert generate_random_number()==987654
  assert generate_random_number()==102938
  assert generate_random_number()==567890
  assert generate_random_number()==999999
output: import random
  
  def generate_random_number():
      return random.randint(100000, 999999)