text: import base64
  import datetime
  from hashlib import sha256
  
  
  def generate_number() -> str:
      """Generate a unique serial number"""
      # Generate a number
      no = sha256(datetime.datetime.now().ctime().encode())
  
      # Return the generated number
      return base64.b64encode(no.digest()).decode()
  
  
  def is_blank(*string: str):
      """Checks if the string is blank"""
      return all(map(lambda x: (x is not None and len(x) > 0), string))
  
  def is_blank_with_default(string: str, default: str):
      """Returns string if it is not blank otherwise return default value"""
      return default if is_blank(string) else string
  