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: ip_cidr_validator.rb
    path of file: ./repos/gitlabhq/app/validators
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

# IpCidrValidator
#
# Validates that an IP is a valid IPv4 or IPv6 CIDR address.
#
# Example:
#
#   class Group < ActiveRecord::Base
#     validates :ip, presence: true, ip_cidr: 
    
  def validate_each(record, attribute, value)
    # NOTE: We want this to be usable for nullable fields, so we don't validate presence.
    #       Use a separate `presence` validation for the field if needed.
    return true if value.blank?

    # rubocop:disable Layout/LineLength -- The error message is bigger than the line limit
    unless valid_cidr_format?(value)
      record.errors.add(
        attribute,
        format(_(
          "IP '%{value}' is not a valid CIDR: IP should be followed by a slash followed by an integer subnet mask (for example: '192.168.1.0/24')"),
          value: value
        )
      )
      return
    end
    # rubocop:enable Layout/LineLength

    IPAddress.parse(value)
  rescue ArgumentError => e
    record.errors.add(
      attribute,
      format(_("IP '%{value}' is not a valid CIDR: %{message}"), value: value, message: e.message)
    )
  end