refactoring: move tokenization to own function

src/parse.rs

@@ -1,9 +1,16 @@
 pub fn parse_line(line: &str) -> (&str, Vec<&str>) {
-    let tokens = line.trim().split(' ').collect::<Vec<&str>>();
-    let mut args: Vec<&str> = Vec::new();
+    let tokens = tokenize(line);
+
     let command = tokens[0];
+    let mut args: Vec<&str> = Vec::new();
+
     if tokens.len() > 1 {
         args = tokens[1..].to_vec();
     }
+
     (command, args)
 }
+
+fn tokenize(line: &str) -> Vec<&str> {
+    line.trim().split(' ').collect::<Vec<&str>>()
+}