input: Write a function to generate prime numbers between 1 and a given number n and print them. If n is less than 2, print an empty list.
  assert generate_prime_numbers(10)
  2
  3
  5
  7
  assert generate_prime_numbers(20)
  2
  3
  5
  7
  11
  13
  17
  19
  assert generate_prime_numbers(1)
  assert generate_prime_numbers(0)
output: def generate_prime_numbers(n):
      if n < 2:
          return
      for num in range(2, n + 1):
          for i in range(2, int(num**0.5) + 1):
              if num % i == 0:
                  break
          else:
              print(num)