MrButek

from functools import reduce
from operator import add

def yolo(arr):
	unique = set
	def concatenate(lists):
		return reduce(add, lists)
	def keys_for(val):
		return [key for key in arr if val in arr[key]]
	def pairs():
		return [(keys_for(val), val) for val in unique(concatenate(arr.values()))]
	result = {}
	for pair in pairs():
		keys, val = ','.join(pair[0]), pair[1]
		if keys not in result:
			result[keys] = []
		result[keys].append(val)
	return result