solana-program-examples/basics/hello-solana/steel/program/src/lib.rs

use solana_program::msg;
use steel::*;

entrypoint!(process_instruction);

fn process_instruction(
    program_id: &Pubkey,
    _accounts: &[AccountInfo],
    _instruction_data: &[u8],
) -> ProgramResult {
    msg!("Hello, Solana!");

    msg!("Our program's Program ID: {}", &program_id);

    Ok(())
}