## 9. Specification functions: `cell-key`

and
`wall-key`

We will need a way to specify a given cell or wall in the
maze. Consequently, we define these Cleanroom
specification functions that specify these key values in a
form that is suitable for use as an index to a Python
dictionary.

mazeratty

# - - - - - S p e c i f i c a t i o n f u n c t i o n s
#================================================================
# cell-key(row, col) ==
# a tuple (row, col) where row is the row number counting
# from 0 at the top and col is the column number counting
# from 0 at the left
#----------------------------------------------------------------
# wall-key(row, col, isV) ==
# if isV is True ->
# the vertical wall to the left of cell-key(row, col)
# else ->
# the horizontal wall above cell-key(row, col)
#----------------------------------------------------------------

So, for example:

The `cell-key`

of the cell in the upper
left corner is `(0,0)`

.

The wall with `wall-key (7,4,0)`

is a
horizontal wall between cell `(6,4)`

and
cell `(7,4)`

.

The wall with `wall-key (7,4,1)`

is a
vertical wall between cell `(7,3)`

and
cell `(7,4)`

.