Returns hourly sentiment index aggregates for the Global Macro Sentiment Indices (GMSI) dataset over the past 24 hours for a given country and topic. Use sentiment_type to switch between directional (topic-specific rules) and semantic sentiment models. Use index_type to filter by domestic or international headline coverage, or return both with COMBINED. Get valid country codes from GET /countries (browse all) or GET /countries/search (search by name). Get valid topics from GET /headlines/topics/gmsi.