मौजूद न होने वाले attributes को एक्सेस करना

class BankAccount:
  def __init__(self, account_number):
    self.account_number = account_number
  
  # Define a magic method to handle references to attribute
  # not in an object's namespace
  def ____(____, ____):
    # Output a message to instruct further action
    print(f"""{____} is not defined in BankAccount object.
    	Please define this attribute if needed.""")
    
# Create a BankAccount object, reference routing_number
checking_account = ____("123456")
____.____