MONKEY GRID

My Python solution to the following challenge:

There is a monkey which can walk around on a planar grid. The monkey can move
one space at a time left, right, up or down.
That is, from (x, y) the monkey can go to (x+1, y), (x-1, y), (x, y+1),
and (x, y-1). Points where the sum of the digits of the absolute value of the
x coordinate plus the sum of the digits of the absolute value of the y
coordinate are lesser than or equal to 19 are accessible to the monkey.

For example, the point (59, 79) is inaccessible because 5 + 9 + 7 + 9 = 30,
which is greater than 19. Another example: the point (-5, -7) is accessible
because abs(-5) + abs(-7) = 5 + 7 = 12, which is less than 19.

How many points can the monkey access if it starts at (0, 0), including
(0, 0) itself?