tagOrId argument specifies
one or more objects on the canvas.
tagOrId argument is an integer,
it is treated as an object ID, and it applies only to
the unique object with that ID. See Section 8.3, “
Canvas object IDs”.
If such an argument is a string, it is interpreted as
a tag, and selects all the objects that have that tag
(if there are any). See Section 8.4, “