Remove useless line breaks

src/main.rs

@@ -110,7 +110,7 @@ fn graphviz_export(tree: &TreeNode) -> String {
 
 fn tex_escape_str(s: &str) -> String {
     s.replace('_', "\\_")
-        .trim_start_matches('\n')
+        .trim_matches('\n')
         .replace("\n\n", "\n")
         .replace('\n', "\\newline\n")
 }