Compare one indicator across 2 to 10 places for the same period, using one shared source and definition whenever possible. Use it for "how does X compare with Y and Z". Places can mix levels, for example a city, a larger city and its region. Example: {"indicator": "registered_unemployment_rate", "places": ["Mataró", "Barcelona", "Cataluña"]}. Returns {indicator, period, comparable, values: [{place, value, period?, status?}], source or sources, notes?}. When comparable is false the values come from different sources (and sometimes periods) and notes explain why; mention it in your answer. For unemployment in municipalities use registered_unemployment_rate: the survey unemployment_rate is not published below province level.