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: mpint.rb
    path of file: ./repos/hrr_rb_ssh/lib/hrr_rb_ssh/data_types
    
    the code of the file until where you have to start completion: module HrrRbSsh
  class DataTypes
    # Mpint provides methods to convert integer value and multiple precision integer in two's complement as binary string each other.
    class Mpint < DataTypes
      # Convert integer value into multiple precision integer in 
    
      def self.decode io
        length = io.read(4).unpack("N")[0]
        hex_str = io.read(length).unpack("H*")[0]
        # get temporal integer value
        value = hex_str.hex
        if length == 0
          0
        elsif value[(length * 8) - 1] == 0
          value
        else
          num_bytes = if hex_str.start_with?("ff") then length - 1 else length end
          - (((~ value) & ((1 << (num_bytes * 8)) - 1)) + 1)
        end