attempt at getting variables to work.

__read.cpp

@@ -4,7 +4,7 @@
 namespace jet {
    
    __read::__read(coreutils::ZString &in, coreutils::MString &out, Global &global) : Tag(in, out, global) {
-      if(!keywordExists(coreutils::ZString("file")))
+      if(!variableDefined(coreutils::ZString("file")))
 	throw coreutils::Exception("file keyword must be specified.");
       
       if(hasContainer)