##Colon labels and attributes
##colon label attributes
##Attributes can come before or after colon labels (or even both)
a->b [label="This is a label", line.width=2];
a->b: This is a label [line.width=2];
a->b [line.width=2]: This is a label;
a->b [line.width=2]: This is a label [color=red];
