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: data_chunk_reader.rb
    path of file: ./repos/wavefile/lib/wavefile/chunk_readers
    
    the code of the file until where you have to start completion: module WaveFile
  module ChunkReaders
    # Internal
    class DataChunkReader < BaseChunkReader    # :nodoc:
      def initialize(io, chunk_size, raw_native_format, format=nil)
        @io = io
        @raw_
    
      def initialize(io, chunk_size, raw_native_format, format=nil)
        @io = io
        @raw_native_format = raw_native_format

        @total_sample_frames = chunk_size / @raw_native_format.block_align
        @current_sample_frame = 0

        @readable_format = true
        begin
          @native_format = @raw_native_format.to_validated_format
          @pack_code = PACK_CODES[@native_format.sample_format][@native_format.bits_per_sample]
        rescue FormatError
          @readable_format = false
          @native_format = nil
          @pack_code = nil
        end