add function file

Rust/functions.rs

@@ -0,0 +1,17 @@
+fn main() {
+    println!("Hello, Satoshi!");
+
+    println!("-----Wallet-----");
+
+    another_function(99999);
+
+    print_labeled_measurement(21000, 's')
+}
+
+fn another_function(x: i32) {
+    println!("The Bitcoin price is {x}");
+}
+
+fn print_labeled_measurement(value: i32, unit_label: char) {
+    println!("Bitcoin Balance : {value}{unit_label}");
+}