@@ -0,0 +1,547 @@
+package org.yi.happy.archive;%0A%0Aimport java.io.PrintStream;%0Aimport java.util.Set;%0A%0Aimport org.yi.happy.archive.commandLine.Env;%0A%0Apublic class HelpMain implements MainCommand %7B%0A    private final PrintStream out;%0A    private final Set%3CString%3E commandNames;%0A%0A    public HelpMain(PrintStream out, Set%3CString%3E commandNames) %7B%0A        this.out = out;%0A        this.commandNames = commandNames;%0A    %7D%0A%0A    @Override%0A    public void run(Env env) throws Exception %7B%0A        for (String name : commandNames) %7B%0A            out.println(name);%0A        %7D%0A    %7D%0A%7D%0A

Add implementation for the help command.