def _composite_options(**kwargs):
    """Return a string representation of options that can be appended to a
    composite metric query
    """
    string = '{'
    num_keys = len(kwargs.keys()) - 1
    for index, key in enumerate(kwargs):
        string += '{}'.format(key)
        string += ': '
        string += '"{}"'.format(kwargs[key])
        if not index >= num_keys:
            string += ', '
    string += '}'
    return string