Today, after hours of hunting a persistent bug in a worksheet, I discovered something i did not know about Maples evaluation strategy. Consider the following Maple code:

restart:
a:=1:
b:=a:
b:=2:
a;

Now the variable 'a' holds the value of 1. Now consider the case where 'a' is a vector:

restart;
a:=<1,1>: