This local transform adds a logging ability to your program using
 Apache Commons logging. Every method call on a unbound variable named 
log
 will be mapped to a call to the logger. For this a 
log field will be
 inserted in the class. If the field already exists the usage of this transform
 will cause a compilation error. The method name will be used to determine
 what to call on the logger.
 
 log.name(exp)
 
is mapped to
 
 if (log.isNameEnabled() {
    log.name(exp)
 }
 Here name is a place holder for info, debug, warning, error, etc.
 If the expression exp is a constant or only a variable access the method call will
 not be transformed. But this will still cause a call on the injected logger.