input: Write a function to print all prime numbers between 1 and a given number n. If the given number n is less than 2 then return None.
  def generate_prime_numbers(n): 
    
      # Array for checking if a number is prime or not
      prime_list = [True for i in range(n + 1)] 
      p = 2
      while (p * p <= n): 
            
          # If prime_list[p] is not changed, then it is a prime 
          if (prime_list[p] == True): 
                
              # Update all multiples of p 
              for i in range(p * 2, n + 1, p): 
                  prime_list[i] = False
          p += 1
    
      # Collecting prime numbers 
      for p in range(2, n): 
          if prime_list[p]: 
              print(p)
  
  assert generate_prime_numbers(20) == None
  assert generate_prime_numbers(10) == None
  assert generate_prime_numbers(1) == None
  assert generate_prime_numbers(0) == None
  assert generate_prime_numbers(-5) == None
output: def generate_prime_numbers(n): 
      if n < 2:
          return None
      
      prime_list = [True for i in range(n + 1)] 
      p = 2
      while (p * p <= n): 
          if (prime_list[p] == True): 
              for i in range(p * 2, n + 1, p): 
                  prime_list[i] = False
          p += 1
    
      for p in range(2, n): 
          if prime_list[p]: 
              print(p)