Add rust example

rust_fib/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "rust_let"
+version = "0.1.0"

rust_fib/Cargo.toml

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+[package]
+name = "rust_let"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

rust_fib/src/main.rs

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+
+use std::io;
+
+fn fib(n: i64) -> i64 {
+    match n {
+        0 => 1,
+        1 => 1,
+        o => fib(o-1) + fib(o-2),
+    }
+}
+
+fn main() {
+    println!("enter number to fib:");
+    let mut buffer = String::new();
+    let stdin = io::stdin();
+    stdin.read_line(&mut buffer).unwrap();
+    println!("{}", fib(buffer.trim().parse::<i64>().unwrap()));
+}