```ruby
require 'net/ssh'
require 'etc'

module Serverspec
  module Helper
    def ssh_exec(host, cmd, opt={})
      options = Net::SSH::Config.for(host)
      user    = options[:user] || Etc.getlogin

      ret = {}
      Net::SSH.start(host, user, options) do |ssh|
        ret = ssh_exec!(ssh, cmd)
      end
      ret
    end

    private
    def ssh_exec!(ssh, command)
      stdout_data = ''
      stderr_data = ''
      exit_code   = nil
      exit_signal = nil
      ssh.open_channel do |channel|
        channel.exec(command) do |ch, success|
          unless success
            abort "FAILED: couldn't execute command (ssh.channel.exec)"
          end
          channel.on_data do |ch,data|
            stdout_data += data
          end

          channel.on_extended_data do |ch,type,data|
            stderr_data += data
          end

          channel.on_request("exit-status") do |ch,data|
            exit_code = data.read_long
          end

          channel.on_request("exit-signal") do |ch, data|
            exit_signal = data.read_long
          end
        end
      end
      ssh.loop
      { :stdout => stdout_data, :stderr => stderr_data, :exit_code => exit_code, :exit_signal => exit_signal }
    end

  end

  module RedHatHelper
    def commands
      Serverspec::Commands::RedHat.new
    end
  end

  module DebianHelper
    def commands
      Serverspec::Commands::Debian.new
    end
  end
end
```

Change default value of ret
user
```ruby
require 'net/ssh'
require 'etc'

module Serverspec
  module Helper
    def ssh_exec(host, cmd, opt={})
      options = Net::SSH::Config.for(host)
      user    = options[:user] || Etc.getlogin

      ret = nil
      Net::SSH.start(host, user, options) do |ssh|
        ret = ssh_exec!(ssh, cmd)
      end
      ret
    end

    private
    def ssh_exec!(ssh, command)
      stdout_data = ''
      stderr_data = ''
      exit_code   = nil
      exit_signal = nil
      ssh.open_channel do |channel|
        channel.exec(command) do |ch, success|
          unless success
            abort "FAILED: couldn't execute command (ssh.channel.exec)"
          end
          channel.on_data do |ch,data|
            stdout_data += data
          end

          channel.on_extended_data do |ch,type,data|
            stderr_data += data
          end

          channel.on_request("exit-status") do |ch,data|
            exit_code = data.read_long
          end

          channel.on_request("exit-signal") do |ch, data|
            exit_signal = data.read_long
          end
        end
      end
      ssh.loop
      { :stdout => stdout_data, :stderr => stderr_data, :exit_code => exit_code, :exit_signal => exit_signal }
    end

  end

  module RedHatHelper
    def commands
      Serverspec::Commands::RedHat.new
    end
  end

  module DebianHelper
    def commands
      Serverspec::Commands::Debian.new
    end
  end
end
```
assistant