py/stream: Add mp_stream_close() helper function.
diff --git a/py/stream.h b/py/stream.h
index 9202c64..b0f45e2 100644
--- a/py/stream.h
+++ b/py/stream.h
@@ -65,6 +65,7 @@
 #define MP_STREAM_OP_IOCTL (4)
 
 const mp_stream_p_t *mp_get_stream_raise(mp_obj_t self_in, int flags);
+mp_obj_t mp_stream_close(mp_obj_t stream);
 
 // Iterator which uses mp_stream_unbuffered_readline_obj
 mp_obj_t mp_stream_unbuffered_iter(mp_obj_t self);