how to make text pop up if you walk in a area in unity 2d code example

Example 1: how do i remove the brackets around a list in python

l = ['a', 2, 'c']
print str(l)[1:-1]
'a', 2, 'c'

Example 2: in unity i want to destroy a gameobject when it hits the edge of the screen

// this does take into account EVERY camera, including the editor view one
// but that shouldn't be a big deal once the game is built

void OnBecameInvisible() {
 	Destroy(gameObject);
}