small rewrite and addition of by_depth + by_depth_test

Cargo.lock

@@ -334,6 +334,12 @@ version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
+[[package]]
+name = "nohash-hasher"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2bf50223579dc7cdcfb3bfcacf7069ff68243f8c363f62ffa99cf000a6b9c451"
+
 [[package]]
 name = "num"
 version = "0.4.3"
@@ -436,6 +442,7 @@ dependencies = [
  "either",
  "indicatif",
  "lazy_static",
+ "nohash-hasher",
  "num",
  "rand",
  "static_assertions",