input: from typing import Optional
  import string
  import random
  
  def generate_random_password(length: int = 8) -> Optional[str]:
      """ Generate a Random Password of given length, which contains at least one of each character type 
      (lowercase, uppercase, digits, special characters). If the length is less than 4, returns None as 
      it's impossible to meet the criteria.
      >>> generate_random_password(8)
      'H7d!#a2T'  # Example output
      >>> generate_random_password(4)
      'H7d!'  # Example output
      >>> generate_random_password(3)
      None
      """
      if length < 4:
          return None
      
      special_characters = "!#$%&'()*+,-./:;<=>?@[\]^_`{|}~"
      password = random.choice(string.ascii_lowercase)
      password += random.choice(string.ascii_uppercase)
      password += random.choice(string.digits)
      password += random.choice(special_characters)
  
      for i in range(length - 4):
          password += random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits + special_characters)
      
      return ''.join(random.sample(password, length))
output:     if length < 4:
          return None
      
      special_characters = "!#$%&'()*+,-./:;<=>?@[\]^_`{|}~"
      password = random.choice(string.ascii_lowercase)
      password += random.choice(string.ascii_uppercase)
      password += random.choice(string.digits)
      password += random.choice(special_characters)
  
      for i in range(length - 4):
          password += random.choice(string.ascii_lowercase + string.ascii_uppercase + string.digits + special_characters)
      
      return ''.join(random.sample(password, length))