kkck: A solver for Kriss Kross puzzles

# - - -   P u z z l e . _ _ c h o i c e F i t s

    def __choiceFits ( self, thisSlot, choice ):
        '''Does choice in thisSlot work with its context?

          [ (thisSlot is a slot in self) and
            (choice is a Word that has the same length as thisSlot) ->
              if choice in thisSlot fits the rest of the puzzle
              according to self.__wordBank ->
                return True
              else -> return False ]
        '''

The purpose of this method is to check all the slots that intersect thisSlot, and test to see that all of the intersecting slots have remaining choices that can connect with thisSlot at the point of intersection.

We'll need to know both the index and the coordinate of each cell in thisSlot, so first we'll materialize a list of the coordinates so we can iterate through both the indices and the coordinates using the list.enumerate() iterator.

        #-- 1 --
        # [ coordList  :=  list of thisSlot's coordinates in order ]
        coordList = [ coord
                      for coord in thisSlot.genCoords() ]

Now we'll step through the coordinates of thisSlot, and for each coordinate, if there is another slot crossing thisSlot there, we call Section 46, “Puzzle.__crossingClash(): Does a perpendicular slot conflict?” to see if the other slot disqualifies this choice. If there are no clashes with crossing slots, we return True.

        #-- 2 --
        # [ if (any Coord in coordList is the intersection of two
        #   slots) and (no choices of the crossing slot match the
        #   corresponding letter of (choice) ->
        #     return False
        #   else -> I ]
        for charx, coord in enumerate(coordList):
            #-- 2 body --
            # [ if (coord is the intersection of two slots in self)
            #   and (no choices for the slot crossing thisSlot have
            #   choice[charx] in coord's position) ->
            #     return False
            #   else -> I ]
            if self.__crossingClash ( coord, thisSlot, choice[charx] ):
                return False

        #-- 3 --
        return True