diff --git a/dev_tools/modules.py b/dev_tools/modules.py
index <HASH>..<HASH> 100644
--- a/dev_tools/modules.py
+++ b/dev_tools/modules.py
@@ -303,6 +303,9 @@ def parse(args):
 
 
 def main(argv: List[str]):
+    if argv == []:
+        # If no arguments are given, print the help/usage info.
+        argv = ['--help']
     args = parse(argv)
     # args.func is where we store the function to be called for a given subparser
     # e.g. it is list_modules for the `list` subcommand
Fix <I>: prevent confusing error if `dev_tools/modules.py` is invoked without arguments (#<I>)

This PR changes `main` in `dev_tools/modules.py` in a very simple way: if the user invokes it without any arguments, it pretends that `--help` was given as the argument instead. This prevents the error described in issue #<I> and makes the whole thing a little bit more user friendly.