finished ch3 started on ch4

functions_rust/Cargo.toml

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+[package]
+name = "functions_rust"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

functions_rust/src/main.rs

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+fn main() {
+    println!("Hello, world!");
+    example_function(1, 4);     // can be delared before or after function that uses it
+}
+
+// fn is the keyword for functions
+fn example_function (x:i8, y:u16) {
+    // type must be delared cannot be inferred
+    // name of parameter/argument is in the brakets seperated by commas
+    // {} show scope of function
+
+    // can be used directly form pram delaration
+    println!("Look anthoer Function {} {y}", x);
+
+}