The equation of the graph shown here is 

A

When $$\ x\leq0, y=+1$$
When $$\ x>0, y=-1$$

B

When$$\ x<0, y=+1$$

When$$\ x\geq0, y=-1$$

C

When$$\ x<0, y=+1$$

When$$\ x>0, y=-1$$

D

When$$\ x<0, y=-1$$

When$$\ x>0, y=+1$$