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: base64_attach.rb
    path of file: ./repos/active-storage-base64/lib/active_storage_support
    
    the code of the file until where you have to start completion: # Helper method to decode a base64 file and create a StringIO file
module ActiveStorageSupport
  module Base64Attach
    module_function

    def a
    
    def fill_attachment_data(attachment, base64_data)
      return unless base64_data.try(:is_a?, String) && base64_data.strip.start_with?('data')

      headers, data = base64_data.split(',')
      decoded_data  = Base64.decode64(data || '')

      attachment[:io] = StringIO.new(decoded_data)
      attachment[:content_type] ||= content_type(headers)
      attachment[:filename]     ||= Time.current.to_i.to_s
    end