diff --git a/mady_macro_core/src/annotator.rs b/mady_macro_core/src/annotator.rs
index b5d2bfc..035be79 100644
--- a/mady_macro_core/src/annotator.rs
+++ b/mady_macro_core/src/annotator.rs
@@ -3,7 +3,7 @@ use std::str::FromStr;
 use crate::error::ParseError;
 use crate::gen::Chain;
 
-use crate::utils::{null, ops_to_string, Marker};
+use crate::utils::{ops_to_string, Marker};
 
 use proc_macro2::TokenStream;
 use syn::parse_quote;
diff --git a/mady_macro_core/src/folder.rs b/mady_macro_core/src/folder.rs
index 25ba57e..1d0136a 100644
--- a/mady_macro_core/src/folder.rs
+++ b/mady_macro_core/src/folder.rs
@@ -6,7 +6,7 @@ use crate::gen::Chain;
 use crate::generator::gen_backward;
 use crate::utils::{grad_method, ops_to_string};
 
-use crate::parser::{Parser, Recorder, Register, VarType};
+use crate::parser::{Parser, Recorder, Register};
 
 #[derive(Default)]
 pub struct Folder;
diff --git a/mady_macro_core/src/lib.rs b/mady_macro_core/src/lib.rs
index 53845f3..6851040 100644
--- a/mady_macro_core/src/lib.rs
+++ b/mady_macro_core/src/lib.rs
@@ -31,7 +31,7 @@ mod tests {
     fn gen() {
         let ts = parse_quote! {
             fn a(a:usize,b:usize) -> usize {
-                a.mul(b) 
+                a.mul(b)
             }
         };
 
diff --git a/mady_macro_core/src/utils.rs b/mady_macro_core/src/utils.rs
index 0a5295b..67783ff 100644
--- a/mady_macro_core/src/utils.rs
+++ b/mady_macro_core/src/utils.rs
@@ -1,4 +1,4 @@
-use crate::graph::{Edge, Graph, Node};
+use crate::graph::Node;
 use crate::parser::{Id, ParseGraph, Var, VarType};
 use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
@@ -77,7 +77,7 @@ impl Marker {
         T: ToString,
     {
         let ty = method_node.to_type_ident();
-        let tys = arg_nodes.into_iter().map(|x| x.to_type_ident());
+        let tys = arg_nodes.iter().map(|x| x.to_type_ident());
         let ty_trait = format_ident!("Grad{}", to_upper_camel_case(method_name.to_string()));
 
         Self {