Add style and compatibility with vim notebook extension

def set_vim_style(theme):
    """Add style and compatibility with vim notebook extension"""

    vim_jupyter_nbext = os.path.join(jupyter_nbext, 'vim_binding')

    if not os.path.isdir(vim_jupyter_nbext):
        os.makedirs(vim_jupyter_nbext)

    vim_less = '@import "styles{}";\n'.format(''.join([os.sep, theme]))

    with open(vim_style, 'r') as vimstyle:
        vim_less += vimstyle.read() + '\n'
    with open(vimtemp, 'w') as vtemp:
        vtemp.write(vim_less)
    os.chdir(package_dir)
    vim_css = lesscpy.compile(vimtemp)
    vim_css += '\n\n'

    # install vim_custom_css to ...nbextensions/vim_binding/vim_binding.css
    vim_custom_css = os.path.join(vim_jupyter_nbext, 'vim_binding.css')
    with open(vim_custom_css, 'w') as vim_custom:
        vim_custom.write(vim_css)