def contextMap(self, kind):
        """Read context maps
        Returns the number of differnt values on the context map
        (In other words, the number of prefix trees)
        """
        NTREES = self.verboseRead(TypeCountAlphabet(
            kind[0].upper()+'T#',
            description='{} prefix trees'.format(kind)))
        mapSize = {L:64, D:4}[kind]
        if NTREES<2:
            self.cmaps[kind] = [0]*mapSize
        else:
            #read CMAPkind
            RLEMAX = self.verboseRead(RLEmaxAlphabet(
                'RLE#'+kind[0].upper(),
                description=kind+' context map'))
            alphabet = TreeAlphabet('CM'+kind[0].upper(), NTREES=NTREES, RLEMAX=RLEMAX)
            cmapCode = self.readPrefixCode(alphabet)
            tableSize = mapSize*self.numberOfBlockTypes[kind]
            cmap = []
            while len(cmap)<tableSize:
                cmapCode.description = 'map {}, entry {}'.format(
                    *divmod(len(cmap), mapSize))
                count, value = self.verboseRead(cmapCode)
                cmap.extend([value]*count)
            assert len(cmap)==tableSize
            IMTF = self.verboseRead(BoolCode('IMTF', description='Apply inverse MTF'))
            if IMTF:
                self.IMTF(cmap)
            if kind==L:
                print('Context maps for literal data:')
                for i in range(0, len(cmap), 64):
                    print(*(
                        ''.join(map(str, cmap[j:j+8]))
                        for j in range(i, i+64, 8)
                        ))
            else:
                print('Context map for distances:')
                print(*(
                    ''.join(map('{:x}'.format, cmap[i:i+4]))
                    for i in range(0, len(cmap), 4)
                    ))
            self.cmaps[kind] = cmap
        return NTREES
Read context maps
        Returns the number of differnt values on the context map
        (In other words, the number of prefix trees)