input: from typing import List
  
  def generate_unique_number() -> int:
      """Generate a unique 6-digit number.
      >>> generate_unique_number()
      12345
      >>> generate_unique_number()
      67890
      """
      import random
      return random.randint(100000, 999999)
output:     import random
      return random.randint(100000, 999999)