def print_commands(self):
        """Print out a help message listing all available commands with a
        description of each.  The list is divided into "standard commands"
        (listed in distutils.command.__all__) and "extra commands"
        (mentioned in self.cmdclass, but not a standard command).  The
        descriptions come from the command class attribute
        'description'.
        """
        import distutils.command

        std_commands = distutils.command.__all__
        is_std = {}
        for cmd in std_commands:
            is_std[cmd] = 1

        extra_commands = []
        for cmd in self.cmdclass.keys():
            if not is_std.get(cmd):
                extra_commands.append(cmd)

        max_length = 0
        for cmd in std_commands + extra_commands:
            if len(cmd) > max_length:
                max_length = len(cmd)

        self.print_command_list(std_commands, "Standard commands", max_length)
        if extra_commands:
            print()
            self.print_command_list(extra_commands, "Extra commands", max_length)
Print out a help message listing all available commands with a
        description of each.  The list is divided into "standard commands"
        (listed in distutils.command.__all__) and "extra commands"
        (mentioned in self.cmdclass, but not a standard command).  The
        descriptions come from the command class attribute
        'description'.
        
product/gradle-plugin/src/main/python/setuptools/_distutils/dist.py