diff --git a/src/main.rs b/src/main.rs
index dc76b42..2987064 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -152,7 +152,7 @@ fn parse_file(file: impl io::Read) -> Result<json::JsonValue, Box<dyn std::error
 
                     ctx.last_keyword_type = ctx.cur_keyword_type;
                     ctx.last_tag = ctx.cur_tag.clone();
-                    ctx.cur_keyword_type = Some(KeywordType::from(&pattern));
+                    ctx.cur_keyword_type = Some(KeywordType::from(pattern));
                     ctx.cur_tag = pattern.replace(' ', "").replace(':', "");
 
                     // remember question id
@@ -218,14 +218,14 @@ fn parse_file(file: impl io::Read) -> Result<json::JsonValue, Box<dyn std::error
 
 // split vector to a vector of [num] slices
 trait SplitTo<T> {
-    fn split_to<'a>(&'a self, num: usize) -> Vec<&'a [T]>;
+    fn split_to(&self, num: usize) -> Vec<&[T]>;
 }
 
 impl<T> SplitTo<T> for Vec<T> {
-    fn split_to<'a>(&'a self, num: usize) -> Vec<&'a [T]> {
+    fn split_to(&self, num: usize) -> Vec<&[T]> {
         let part_len = self.len() / num;
         let add_len = self.len() % num;
-        let mut result = Vec::<&'a [T]>::with_capacity(num);
+        let mut result = Vec::<&[T]>::with_capacity(num);
 
         if 0 == part_len {
             result.push(self);
@@ -246,7 +246,7 @@ impl<T> SplitTo<T> for Vec<T> {
 
 
 fn process_files(files: &&[PathBuf]) {
-    if files.len() < 1 {
+    if files.is_empty() {
         return;
     }