extern crate txtpic;
use txtpic::calculate_string_brightness::calculate_string_brightness;

fn main() {
    println!("{}", calculate_string_brightness('M'));
    println!("{}", calculate_string_brightness('@'));
    println!("{}", calculate_string_brightness('%'));
    println!("{}", calculate_string_brightness('#'));
    println!("{}", calculate_string_brightness('x'));
    println!("{}", calculate_string_brightness('+'));
    println!("{}", calculate_string_brightness('='));
    println!("{}", calculate_string_brightness(':'));
    println!("{}", calculate_string_brightness('-'));
    println!("{}", calculate_string_brightness('.'));
    println!("{}", calculate_string_brightness(' '));
}

extern crate txtpic;
use txtpic::calculate_string_brightness::calculate_string_brightness;

fn main() {
    println!("{}", calculate_string_brightness("@"));
    println!("{}", calculate_string_brightness("%"));
    println!("{}", calculate_string_brightness("#"));
    println!("{}", calculate_string_brightness("x"));
    println!("{}", calculate_string_brightness("+"));
    println!("{}", calculate_string_brightness("="));
    println!("{}", calculate_string_brightness(":"));
    println!("{}", calculate_string_brightness("-"));
    println!("{}", calculate_string_brightness("."));
    println!("{}", calculate_string_brightness(" "));
}

--- 
+++ 
@@ -2,14 +2,15 @@
 use txtpic::calculate_string_brightness::calculate_string_brightness;
 
 fn main() {
-    println!("{}", calculate_string_brightness("@"));
-    println!("{}", calculate_string_brightness("%"));
-    println!("{}", calculate_string_brightness("#"));
-    println!("{}", calculate_string_brightness("x"));
-    println!("{}", calculate_string_brightness("+"));
-    println!("{}", calculate_string_brightness("="));
-    println!("{}", calculate_string_brightness(":"));
-    println!("{}", calculate_string_brightness("-"));
-    println!("{}", calculate_string_brightness("."));
-    println!("{}", calculate_string_brightness(" "));
+    println!("{}", calculate_string_brightness('M'));
+    println!("{}", calculate_string_brightness('@'));
+    println!("{}", calculate_string_brightness('%'));
+    println!("{}", calculate_string_brightness('#'));
+    println!("{}", calculate_string_brightness('x'));
+    println!("{}", calculate_string_brightness('+'));
+    println!("{}", calculate_string_brightness('='));
+    println!("{}", calculate_string_brightness(':'));
+    println!("{}", calculate_string_brightness('-'));
+    println!("{}", calculate_string_brightness('.'));
+    println!("{}", calculate_string_brightness(' '));
 }
Use new API in test code
