You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: bank_account.rb
    path of file: ./repos/catarse/app/models
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
re
    
  def account_digit_validation

    errors.delete :account_digit

    if account_digit == nil || account_digit.length == 0
      errors.add(:account_digit, :blank)
      return false
    end