Suppose we wish to determine which countries exist in both the POIs data and the cities data. Implement the function, def get_common_ccs(pois, cities): ... to complete this task. Inputs: pois: POIs, stored in a Python dictionary of dictionaries, mapping POI IDs keys to attribute values (like earlier examples) cities: City records, stored in a Python dictionary of dictionaries, mapping city names to attribute values (like earlier examples) You may assume that the inner dictionaries have the same four keys: 'country_code', 'lat', 'long', and 'type'. Task: Identify all country codes that exist in pois and in cities. Outputs: Return a new Python set consisting of the common country codes. In Python..