From c8fc83dacf36cc01b4ffbec3c029cd2e84de79f6 Mon Sep 17 00:00:00 2001
From: Ethan Dalool <git@voussoir.net>
Date: Wed, 24 Jun 2020 22:26:27 -0700
Subject: [PATCH] Add stricter requirement that callable returns 0 or None.

Not just any falsey value will do.
---
 rarpar.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/rarpar.py b/rarpar.py
index 1c3d365..da4af11 100644
--- a/rarpar.py
+++ b/rarpar.py
@@ -190,6 +190,13 @@ def normalize_volume(volume, pathsize):
     return volume
 
 def run_script(script, dry=False):
+    '''
+    `script` can be a list of strings, which are command line commands, or
+    callable Python functions. They will be run in order, and the sequence
+    will terminate if any step returns a bad status code. Your Python functions
+    must return either 0 or None to be considered successful, all other return
+    values will be considered failures.
+    '''
     status = 0
 
     if dry:
@@ -203,8 +210,7 @@ def run_script(script, dry=False):
             status = os.system(command)
         else:
             status = command()
-            status = status or 0
-        if status != 0:
+        if status not in [0, None]:
             break
 
     return status