mnemonic-protocol/protocol/src/lib.rs

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// Define a function named `add` that takes two `usize` parameters and returns a `usize` result
pub fn add(left: usize, right: usize) -> usize {
    // Add the left and right parameters together and return the result
    left + right
}

// Define a module named `tests` that contains unit tests for the `add` function
#[cfg(test)]
mod tests {
    // Import items from the outer scope (including the `add` function)
    use super::*;

    // Define a unit test named `it_works` that checks if the `add` function produces the expected result
    #[test]
    fn it_works() {
        // Call the `add` function with parameters 2 and 2
        let result = add(2, 2);

        // Assert that the result is equal to 4
        assert_eq!(result, 4);
    }
}