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: sql.rb
    path of file: ./repos/zammad/lib/selector
    
    the code of the file until where you have to start completion: # Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class Selector::Sql < Selector::Base
  VALID_OPERATORS = [
    'after
    
  def validate_pre_condition_values!(condition)
    return if ['has changed', 'has reached', 'has reached warning'].include? condition[:operator]
    return if condition[:pre_condition].blank?
    return if %w[not_set current_user. specific].any? { |elem| condition[:pre_condition].start_with? elem }

    raise InvalidCondition, "Invalid condition pre_condition not set #{condition}!"
  end