for 'a' in 'c.' This operation is analogous to $(subst) in GNU make.
``!foreach(a, b, c)``
- For each member 'b' of dag or list 'a' apply operator 'c.' 'b' is a dummy
+ For each member of dag or list 'b' apply operator 'c.' 'a' is a dummy
variable that should be declared as a member variable of an instantiated
class. This operation is analogous to $(foreach) in GNU make.