Added functions for chapter 4

src/VariableBindings/ScopeAndShadowing.rs

@@ -0,0 +1,29 @@
+pub fn main(){
+	// This binding lives in the main function
+	let long_lived_binding = 1;
+
+	// This is a block, and has a smaller scope than the main function
+	{
+		// This binding only exists in this block
+		let short_lived_binding = 2;
+
+		println!("inner short: {}", short_lived_binding);
+
+		// This binding *shadows* the outer one
+		let long_lived_binding = 5_f32;
+
+		println!("inner long: {}", long_lived_binding);
+	}
+	// End of the block
+
+	// Error! `short_lived_binding` doesn't exist in this scope
+	//println!("outer short: {}", short_lived_binding);
+	// FIXME ^ Comment out this line
+
+	println!("outer long: {}", long_lived_binding);
+	
+	// This binding also *shadows* the previous binding
+	let long_lived_binding = 'a';
+	
+	println!("outer long: {}", long_lived_binding);
+}