reuse existing function

src/colour.rs

@@ -9,9 +9,7 @@ pub struct Colour {
 
 impl From<&str> for Colour {
     fn from(str: &str) -> Self {
-        let rgb = hex::decode(&str[str.len() - 6..]).unwrap();
-
-        Colour { red: rgb[0], green: rgb[1], blue: rgb[2] }
+        Self::from(hex::decode(&str[str.len() - 6..]).unwrap())
     }
 }