let c = 'a';
let is_letter = c.is_alphabetic();
let is_number = c.is_digit(10);
//is_letter is true
//is_number is false
let c2 = '$';
let symbol_list = "@#$%^&*";
let is_in_list = symbol_list.contains(c2);
//is_in_list is true
println!("is_letter is {is_letter}");
println!("is_number is {is_number}");
println!("is_in_list is {is_in_list}");