Assignment is an operator not a statement, it returns a value.
Assigment is right associative. i = j = k; :=
i = (j = k);
As seen before, however we say that v += e is NOT
equivalant to v = v + e. Pay attention to how many times v
is called. For example
This is due to order of precedence, as well as side_effects. They are
also right associative, and can be chained. i += j += k;
:= i += (j += k); # standard wood