Validation baseline.

src/plugin.rs

@@ -4,6 +4,15 @@ use std::io;
 
 pub trait Plugin {
     fn config(&mut self) -> Result<CommandConfig, ShellError>;
+
+    #[allow(unused)]
+    fn is_valid(&self) -> bool { 
+        true
+    }
+
+    #[allow(unused)]
+    fn log_error(&mut self, message: &str) { }
+
     #[allow(unused)]
     fn begin_filter(&mut self, call_info: CallInfo) -> Result<Vec<ReturnValue>, ShellError> {
         Ok(vec![])