code: def numberMapForBits(self, bits):
      
      numberMap = dict()
  
      for bit in bits:
        numbers = self.numbersForBit(bit)
  
        for number in numbers:
          if not number in numberMap:
            numberMap[number] = set()
  
          numberMap[number].add(bit)
  
      return numberMap
docs: Return a map from number to matching on bits,
      for all numbers that match a set of bits.
  
      @param bits (set) Indices of bits
  
      @return (dict) Mapping from number => on bits.