remove unused imports

src/builtin/mkdir.rs

@@ -2,12 +2,12 @@ use crate::{
     error::ExecError,
     run::{Call, Context, Value},
 };
-use std::{env, fs, io::Write};
+use std::fs;
 
 pub struct Mkdir;
 
 impl Call for Mkdir {
-    fn call(&self, ctx: &mut Context, args: &[Value]) -> Result<Value, ExecError> {
+    fn call(&self, _ctx: &mut Context, args: &[Value]) -> Result<Value, ExecError> {
         match args.len() {
             0 => {
                 todo!()