Question 56415
 y=[x+3]
If your brackets mean "absolute value" the 
graph is not a step function.  Step functions
have a discontinuous pattern, like a step.
Your function looks like the letter V.
To see what it looks like plot a few points:
y=|x+3|
If x=-5 you get y=|-5+3|=2 giving point (-5,2)
If x=-4 you get y=|-4+3|=1 giving point (-4,1)
If x=-3 you get y=0 giving point (-3,0)
If x=-2 then y=|1|=1 giving point (-2,1)
If x=-1 then y=|2|=2 giving point (-1.2)
If x=0 you get point(0,3)
Plot these point and you will see the V shape
of the graph.
Cheers,
Stan H.