Add an export

    CLI Example:

    .. code-block:: bash

        salt '*' nfs3.add_export path='/srv/test' hosts='127.0.0.1' options=['rw']

def add_export(exports='/etc/exports', path=None, hosts=None, options=None):
    '''
    Add an export

    CLI Example:

    .. code-block:: bash

        salt '*' nfs3.add_export path='/srv/test' hosts='127.0.0.1' options=['rw']
    '''
    if options is None:
        options = []
    if not isinstance(hosts, six.string_types):
        # Lists, etc would silently mangle /etc/exports
        raise TypeError('hosts argument must be a string')
    edict = list_exports(exports)
    if path not in edict:
        edict[path] = []
    new = {'hosts': hosts, 'options': options}
    edict[path].append(new)
    _write_exports(exports, edict)

    return new