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: mp3_file.rb
    path of file: ./repos/alonetone/app/models/upload
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

class Upload
  # Service class to build Asset instances based on the MP3 data.
  class Mp3File
    include ActiveModel::Model

    # File with the uploaded file data. Note that this may be a Tempfile
    # generated
    
    def combined_attributes
      asset_attributes
        .merge(title: title_from_filename)
        .merge(metadata.attributes)
        .merge(
          user: user,
          audio_file: {
            io: file,
            filename: filename,
            content_type: content_type
          }.compact
        )
    end