/in/ex6.cpp: In function 'std::ostream& operator<<(std::ostream&, const BinaryTree&)':
/in/ex6.cpp:80:1: error: no return statement in function returning non-void [-Werror=return-type]
 }
 ^
/in/ex6.cpp: In member function 'TreeNode* BinaryTree::copy(TreeNode*)':
/in/ex6.cpp:88:1: error: no return statement in function returning non-void [-Werror=return-type]
 }
 ^
cc1plus: all warnings being treated as errors
/in/compile/Makefile:69: recipe for target 'ex6.o' failed
make: *** [ex6.o] Error 1