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: birthday.rb
    path of file: ./repos/diaspora_federation/lib/diaspora_federation/validators/rules
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require "date"

module Validation
  module Rule
    # Birthday validation 
    
      def valid_value?(value)
        return true if value.nil? || (value.is_a?(String) && value.empty?)
        return true if value.is_a? Date

        if value.is_a?(String) && value.match?(/[0-9]{4}-[0-9]{2}-[0-9]{2}/)
          date_field = value.split("-").map(&:to_i)
          return Date.valid_civil?(date_field[0], date_field[1], date_field[2])
        end