gistfile1.py

list_or_string = (t.List(t.String(allow_blank=True)) >> first) | t.String(allow_blank=True)
check_comma_string = list_or_string >> (lambda s: s.split(',')) >> t.List(t.String(allow_blank=True) >> str.strip)

list_or_string_date = (t.List(t.String(allow_blank=True)) >> first) | t.String(allow_blank=True)


parse_ga_qs = t.Dict({
    t.Key('start-date') >> 'start': list_or_string_date,
    t.Key('end-date') >> 'end': list_or_string_date,
    t.Key('dimensions', optional=True): check_comma_string,
    t.Key('metrics', optional=True): check_comma_string,
    t.Key('segment', optional=True): check_comma_string,
    t.Key('filters', optional=True): check_comma_string,
    t.Key('sort', optional=True): check_comma_string,
    t.Key('range', optional=True): list_or_string_date,
}).ignore_extra('max-results', 'api_url')