made reference to leetcode struct immutable

Signed-off-by: dvishal485 <dvishal485@gmail.com>

Author: dvishal485

src/leetcode_api/leetcode.rs

@@ -25,7 +25,7 @@ impl LeetCode {
 impl LeetCode<Unauthorized> {
     /// # Authenticate with cookie
     /// Builds a new reqwest client with the cookie
-    pub fn authenticate(&mut self, cookie: &str) -> Result<LeetCode<Authorized>, &str> {
+    pub fn authenticate(&self, cookie: &str) -> Result<LeetCode<Authorized>, &str> {
         let mut headers = reqwest::header::HeaderMap::with_capacity(5);
         let Some(csrf_token) = cookie
    .split(';')

src/main.rs

@@ -80,8 +80,8 @@ fn main() -> ExitCode {
         return ExitCode::FAILURE;
     };
 
-    let mut leetcode = LeetCode::new();
-    let lc = leetcode.authenticate(cookie).unwrap();
+    let lc = LeetCode::new();
+    let lc = lc.authenticate(cookie).unwrap();
 
     if let None = cli.command {
         println!(