Name the functional group

You will write functions that decide which functional group a compound has from the set of its positive tests. The tests are named by short strings, such as "DNP" for 2,4-dinitrophenylhydrazine.

The idea. A positive 2,4-DNP test shows a carbonyl compound. If Tollens' reagent is also positive, it is an aldehyde. If sodium hydrogencarbonate gives effervescence, the compound is a carboxylic acid. A violet colour with neutral iron(III) chloride shows a phenol.

Your tasks.

1. Complete carbonyl_type(tests). It returns "aldehyde", "ketone" or None.
2. Complete acid_or_phenol(tests). It returns "carboxylic acid" when "NaHCO3" is in the set, "phenol" when "FeCl3" is in it, and None otherwise.
3. Complete group(tests). It returns the carbonyl type if there is one, else the answer of task 2, else "unknown".