Initial data commit

Task/Null-object/Icon/null-object.icon

@@ -0,0 +1,10 @@
+procedure main()
+nulltest("a",a)                # unassigned variables are null by default
+nulltest("b",b := &null)       # explicit assignment is possible
+nulltest("c",c := "anything")
+nulltest("c",c := &null)       # varibables can't be undefined
+end
+
+procedure nulltest(name,var)
+return write(name, if /var then " is" else " is not"," null.")
+end