def load (filename):
    """Loads the two dimensional Conway Cubes puzzle input and returns a
    mapping of all active coordinates, i.e. `active[coord] = True`.
    """
    active = { }

    with open(filename) as stream:
        for y, line in enumerate( stream.readlines() ):
            line = line.strip()
            for x, c in enumerate(line):
                if c == '#':
                    active[(x, y)] = True

    return active