diff --git a/practical.yml b/practical.yml
index 29b8792..46cf5d7 100644
--- a/practical.yml
+++ b/practical.yml
@@ -3,7 +3,9 @@ name: "strings internals"
 subject: "subject_text"
 source: "subject_source"
 tag_every: "2min"
-file_check_ignore: []
+file_check_ignore:
+  - "tests/"
+  - "Cargo.lock"
 to_copy:
   - "Cargo.toml"
   - "tests/"
diff --git a/subject_text/tree b/subject_text/tree
new file mode 100644
index 0000000..af5deae
--- /dev/null
+++ b/subject_text/tree
@@ -0,0 +1,7 @@
+.
+├── Cargo.toml
+└── src
+    ├── errors
+    │   └── option.rs
+    ├── errors.rs
+    └── lib.rs