Update readme and another tutorial

README.md

@@ -1 +1,3 @@
 # literate-tribble
+
+## Rust toy programs and tutorials

adder/Cargo.lock

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+[root]
+name = "adder"
+version = "0.1.0"
+

adder/Cargo.toml

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+[package]
+name = "adder"
+version = "0.1.0"
+authors = ["Tim Warren <twarren@nexient.com>"]

adder/src/lib.rs

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+//! The `adder` crate provides functions that add numbers to other numbers
+//!
+//! # Examples
+//!
+//! ```
+//! assert_eq!(4, adder::add_two(2));
+//! ```
+
+/// This function adds two to its argument
+///
+/// # Examples
+///
+/// ```
+/// use adder::add_two;
+///
+/// assert_eq!(4, add_two(2));
+/// ```
+pub fn add_two(a: i32) -> i32 {
+	a + 2 // return
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn it_works() {
+		assert_eq!(4, add_two(2));
+	}
+}

adder/tests/lib.rs

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+extern crate adder;
+
+#[test]
+fn it_works() {
+	assert_eq!(4, adder::add_two(2));
+}