keep.c: (in function f2)
keep.c:12:9: Keep storage passed as only param: free (x)
   keep.c:10:26: Storage x becomes keep
keep.c: (in function f3)
keep.c:19:27: Keep storage x not transferred before return
   keep.c:15:25: Storage x becomes keep
keep.c: (in function f5)
keep.c:36:10: Keep storage x not transferred before return
   keep.c:34:39: Storage x becomes keep
keep.c: (in function f6)
keep.c:44:5: Variable x is kept in true branch, but not kept in continuation.
   keep.c:44:5: in true branch:
   keep.c:43:11: Storage x becomes kept
   keep.c:44:5: in continuation:
   keep.c:39:26: Storage x becomes keep
keep.c:46:7: Kept storage x passed as keep param: f2 (x)
   keep.c:44:5: Storage x becomes kept
keep.c: (in function f7)
keep.c:60:10: Kept storage x returned as implicitly only: x
   keep.c:58:5: Storage x becomes kept

Finished checking --- 6 code warnings, as expected