fn initialize(env: soroban_sdk::Env, admin: soroban_sdk::Address)
fn send_message(
env: soroban_sdk::Env,
sender: soroban_sdk::Address,
content: soroban_sdk::String,
) -> u32
fn get_message(env: soroban_sdk::Env, message_id: u32) -> Message
fn get_message_count(env: soroban_sdk::Env) -> u32
fn get_messages_by_sender(
env: soroban_sdk::Env,
sender: soroban_sdk::Address,
limit: u32,
) -> soroban_sdk::Vec<(u32, Message)>
fn get_recent_messages(
env: soroban_sdk::Env,
limit: u32,
) -> soroban_sdk::Vec<(u32, Message)>
fn get_admin(env: soroban_sdk::Env) -> soroban_sdk::Address