dim_cube.py

def verticals(arg): # making the verticals
    print('|         ' * arg, '|')
    
def do_four_times(f, arg): # 4 times repeater
    f(arg)
    f(arg)
    f(arg)
    f(arg)
    
def onestroke(dim, vert_func): # make one row
    print('+ - - - - ' * dim, '+') # first, the line with the +'s
    do_four_times(vert_func, dim) # then the 4 verticals
    
def dimstrokes(f, dim, one_func): # make "dim" rows
    x = 1
    while x <= dim:
        f(dim, one_func)
        x += 1
        
def draw_square(dim):
    dimstrokes(onestroke, dim, verticals) # calling it
    print('+ - - - - ' * dim, '+') # closing it off
          
draw_square(6)

Very nice solution! I might rename the parameters a and b to clarify their roles.

(And I think the while loop is a bit of a cheat, since it doesn't appear in the book until after this exercise. )

Still, good stuff -- thanks!

Thanks for the input!

I changed the a to dim and the b to either vert_func or one_func to avoid confusion.