Fix bugs

src/types.h

@@ -116,6 +116,9 @@ GroundInstruction createGroundInstruction(GroundInstType type);
 // Frees all data stored on the heap in a GroundInstruction.
 void freeGroundInstruction(GroundInstruction* gi);
 
+// Creates a deep copy of a GroundInstruction.
+GroundInstruction copyGroundInstruction(const GroundInstruction* gi);
+
 // Adds arg (arg) to the GroundInstruction (gi).
 void addArgToInstruction(GroundInstruction* gi, GroundArg arg);