Load observing mode OB tagger

def load_mode_tagger(obs_mode, node):
    """Load observing mode OB tagger"""

    # handle tagger:
    ntagger = node.get('tagger')

    if ntagger is None:
        pass
    elif isinstance(ntagger, list):

        def full_tagger(obsres):
            return get_tags_from_full_ob(obsres, reqtags=ntagger)

        obs_mode.tagger = full_tagger
    elif isinstance(ntagger, six.string_types):
        # load function
        obs_mode.tagger = import_object(ntagger)
    else:
        raise TypeError('tagger must be None, a list or a string')

    return obs_mode