'Clean the build environment.'

def Clean(self):

    if os.path.exists(args.build_dir):
        subprocess.call(('rd    /s    /q    %s' % args.build_dir), shell=True)
    if os.path.exists(args.output_dir):
        subprocess.call(('rd    /s    /q    %s' % args.output_dir), shell=True)
    os.makedirs(args.build_dir)
    os.makedirs(args.output_dir)
    subprocess.check_call([self.virtualenv_bin64, self.virtualenv64])
    if args.build_32:
        subprocess.check_call([self.virtualenv_bin32, self.virtualenv32])
    cmd = ['-m', 'pip', 'install']
    if args.wheel_dir:
        cmd += ['--no-index', ('--find-links=file:///%s' % args.wheel_dir)]
    subprocess.check_call((([self.virtualenv_python64] + cmd) + ['--upgrade', 'pip>=8.1.1']))
    if args.build_32:
        subprocess.check_call((([self.virtualenv_python32] + cmd) + ['--upgrade', 'pip>=8.1.1']))
    os.environ['PROTOC'] = args.protoc
