input: Write a function to print all prime numbers between 1 and a given number n. If n is less than 2, the function should print nothing.
  
  assert generate_prime_numbers(10)
  assert generate_prime_numbers(20)
  assert generate_prime_numbers(1)
  assert generate_prime_numbers(-5)
output: def generate_prime_numbers(n):
      if n < 2:
          return
      primes = []
      for num in range(2, n + 1):
          for i in range(2, int(num**0.5) + 1):
              if num % i == 0:
                  break
          else:
              primes.append(num)
      print(primes)