if(interactive()){
readline_check("Type a number: ", "numeric")
readline_check("Type two characters: ", "length", min = 2, max = 2)
readline_check("Type at least 3 characters: ", "length", min = 3)
readline_check("Type no more than 4 characters: ", "length", max = 44)
readline_check("Type a letter and a number: ", "grep", pattern = "^[a-zA-Z]\\d$")
}
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