decman.modules should be a list

example/README.md

@@ -85,7 +85,7 @@ import decman
 from base import BaseModule
 
 decman.pacman.packages |= {"openssh", "qemu-guest-agent", "sudo", "vim"}
-decman.modules |= {BaseModule()}
+decman.modules += [BaseModule()]
 ```
 
 This config is already enough to run decman for the first time.
@@ -162,7 +162,7 @@ from kde import KDE
 
 ...
 
-decman.modules |= {BaseModule(), KDE()}
+decman.modules += [BaseModule(), KDE()]
 ```
 
 I'll run decman once again. I'll also start SDDM manually, since decman can't autostart it.

example/plugin/decman_plugin_example.py

@@ -9,7 +9,7 @@ class Example(decman.Plugin):
     def available(self) -> bool:
         return os.path.exists("/tmp/example_plugin_available")
 
-    def process_modules(self, store: decman.Store, modules: set[decman.Module]):
+    def process_modules(self, store: decman.Store, modules: list[decman.Module]):
         # Toy example for setting modules as changed
         for module in modules:
             module._changed = True

example/source.py

@@ -5,7 +5,7 @@ import decman
 
 decman.pacman.packages |= {"openssh", "qemu-guest-agent", "sudo", "vim"}
 
-decman.modules |= {BaseModule(), KDE()}
+decman.modules += [BaseModule(), KDE()]
 
 decman.files["/home/arch/.vimrc"] = decman.File(
     source_file="./files/vimrc", owner="arch", permissions=0o600