pub fn say_hello(name: &str)-> String{
format!("Hello, {}!", name)
}
pub fn say_goodbye(name: &str)-> String{
format!("Goodbye, {}!", name)
}
pub fn say_hello_to_everyone()-> String{
"Hello, everyone!".to_string()
}
pub fn say_goodbye_to_everyone()-> String{
"Goodbye, everyone!".to_string()
}