+The three modes are exclusives.
+
+The default mode is `--project` unless one on the argument is a group, then it is `--group`.
+
+## COLLECT
+
+`-r`, `--recursive`
+: Process directories recursively.
+
+ All `.nit` files found in the specified directory and subdirectories are considered.
+
+`-d`, `--depends`
+: List dependencies of given modules
+
+ All imported modules are also considered.
+
+ In --tree and --source modes, the modules direclty imported are also displayed.
+
+`-k`, `--keep`
+: Ignore errors and files that are not a Nit source file.
+
+ When a file that is not a valid Nit module is encoutered, it is ignored and the rest of the files are
+ processed.
+
+ Without this option, an error message is displayed and nitls terminates on such a case.
+