Write a function that computes the area of a triangle given its base and height.

The formula for an area of a triangle is:

AREA $=\frac{1}{2}**$ BASE $**$ HEIGHT

For example, if the base was $5$ and the height was $4,$ the area would be $10.$ triangle$\_$area $(5,4)$; # should print $10$

Your function must be named triangle$\_$area

Note: Be sure to include comments for all functions that you use or create.