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: colors.rb
    path of file: ./repos/letter_avatar/lib/letter_avatar
    
    the code of the file until where you have to start completion: require 'digest' 

module LetterAvatar
  module Colors
    PALETTES = [:google, :iwant
    
		def self.valid_custom_palette?(palette)
			return false unless palette.is_a?(Array)
			return palette.all? do |color| 
				false unless color.is_a?(Array)
				color.all? { |i| i.is_a?(Integer) }
			end
		end