Use cli = self approach

lib/mrsk/sshkit_with_ext.rb

@@ -1,17 +1,7 @@
 require "sshkit"
 require "sshkit/dsl"
 
-module AppHelper
-  def stale_versions(role:)
-    capture_with_info(*MRSK.app(role: role).list_versions, raise_on_non_zero_exit: false)
-      .split("\n")
-      .drop(1)
-  end
-end
-
 class SSHKit::Backend::Abstract
-  include AppHelper
-
   def capture_with_info(*args, **kwargs)
     capture(*args, **kwargs, verbosity: Logger::INFO)
   end