forest seems to be completed

I seem to have finished the implementation of forests.  Now it remains
the implementation of the chain-rule machine, of which I have a rough
plan now.

1 files changed, 6 insertions, 0 deletions

diff --git a/forest/Cargo.toml b/forest/Cargo.toml
index b88451d..c51bf36 100644
--- a/forest/Cargo.toml
+++ b/forest/Cargo.toml
@@ -5,5 +5,11 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
+[features]
+default = []
+
+# This flag controls whether to print GraphViz files during testing.
+test-print-viz = []
+
 [dependencies]
 graph = { path = "../graph" }