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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def build_mmd(target_folder=DEFAULT_LIBRARY_DIR):
 """Build and install the MultiMarkdown shared library."""

    mmd_dir = tempfile.mkdtemp()
    mmd_repo = pygit2.clone_repository('https://github.com/jasedit/MultiMarkdown-5', mmd_dir,
                                       checkout_branch='fix_windows')
    mmd_repo.init_submodules()
    mmd_repo.update_submodules()
    build_dir = os.path.join(mmd_dir, 'build')
    old_pwd = os.getcwd()
    os.chdir(build_dir)

    cmake_cmd = ['cmake', '-DCMAKE_BUILD_TYPE=Release', '-DSHAREDBUILD=1', '..']
    if platform.system() == 'Windows':
        is_64bit = platform.architecture()[0] == '64bit'
        generator = 'Visual Studio 14 2015{0}'.format(' Win64' if is_64bit else '')
        cmake_cmd.insert(-1, '-G')
        cmake_cmd.insert(-1, '{0}'.format(generator))
    subprocess.call(cmake_cmd)
    PLATFORM_BUILDS[platform.system()]()

    lib_file = 'libMultiMarkdown' + SHLIB_EXT[platform.system()]
    if not os.path.exists(target_folder):
        os.mkdir(target_folder)
    src = os.path.join(build_dir, SHLIB_PREFIX[platform.system()], lib_file)
    dest = os.path.join(target_folder, lib_file)
    shutil.copyfile(src, dest)
    os.chdir(old_pwd)
    shutil.rmtree(mmd_dir, ignore_errors=True)