Clarify lifetimes in search function in chapter 12.4

listings/ch12-an-io-project/listing-12-16/src/lib.rs

@@ -1,5 +1,5 @@
 // ANCHOR: here
-pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+pub fn search<'a, 'b>(query: &'a str, contents: &'b str) -> Vec<&'b str> {
     vec![]
 }
 // ANCHOR_END: here

listings/ch12-an-io-project/listing-12-17/src/lib.rs

@@ -1,5 +1,5 @@
 // ANCHOR: here
-pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+pub fn search<'a, 'b>(query: &'a str, contents: &'b str) -> Vec<&'b str> {
     for line in contents.lines() {
         // do something with line
     }

listings/ch12-an-io-project/listing-12-18/src/lib.rs

@@ -1,5 +1,5 @@
 // ANCHOR: here
-pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+pub fn search<'a, 'b>(query: &'a str, contents: &'b str) -> Vec<&'b str> {
     for line in contents.lines() {
         if line.contains(query) {
             // do something with line

listings/ch12-an-io-project/listing-12-19/src/lib.rs

@@ -1,6 +1,6 @@
 // ANCHOR: here
 // ANCHOR: ch13
-pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
+pub fn search<'a, 'b>(query: &'a str, contents: &'b str) -> Vec<&'b str> {
     let mut results = Vec::new();
 
     for line in contents.lines() {