$13.$ Add Vertical Flipping

Extend your implementation of the function flip to include the case vertical is True. Use an if$-$statement to make sure that you do not break horizontal flipping. Your function should flip horizontally when vertical is False and vertically when it is True.

To test out vertical flipping, you will need to execute pictool.py with the vertical option, adding $--$vertical$=$True to the end of the command line. For example, executing the command

python pictool.py flip images$/$Walker$.$png Walker$2.$png $--$vertical$=$True

should perform the following conversion:

Important: Because you can put anything you want in the vertical option $($say $--$vertical$=$blue$),$ we recommend that you enforce the precondition for vertical in the function with assert statements.

def flip$($image$,$vertical$=$False$)$:

$"""$

Returns True after reflecting the image horizontally or vertically.

All plug$-$in functions must return True or False. This function returns True

because it modifies the image. By default it reflects the image horizonally,

or vertically if vertical is True.

Parameter image: The image buffer

Precondition: image is a $2$d table of RGB objects

Parameter vertical: Whether to reflect the image vertically

Precondition: vertical is a bool

$"""$

# We recommend enforcing the precondition for vertical

assert isinstance$($vertical$,$ bool$)$

rows $=$ len$($image$)$

cols $=$ len$($image$[0])$

if not vertical:

for row in image:

row.reverse$()$

else:

image.reverse$()$

# Change this to return True when the function is implemented

return True