(boolean? true) -> true
(boolean? false) -> true
(boolean? 1) -> false
(boolean? 5) -> false
(boolean? "string") -> false
(boolean? (+ 1 2 3)) -> false
(boolean? (not 1)) -> true
(nil? true) -> false
(nil? false) -> false
(nil? 1) -> false
(nil? 5) -> false
(nil? "string") -> false
(nil? (+ 1 2 3)) -> false
(nil? (not 1)) -> false
(nil? ()) -> true
(string? true) -> false
(string? false) -> false
(string? 1) -> false
(string? 5) -> false
(string? "string") -> true
(string? (+ 1 2 3)) -> false
(string? (not 1)) -> false
(fixnum? true) -> false
(fixnum? false) -> false
(fixnum? 1) -> true
(fixnum? 5) -> true
(fixnum? "string") -> false
(fixnum? (+ 1 2 3)) -> true
(fixnum? (not 1)) -> false
(symbol? true) -> false
(symbol? false) -> false
(symbol? 1) -> false
(symbol? +) -> false
(symbol? "string") -> false
(symbol? (+ 1 2 3)) -> false
(symbol? (not 1)) -> false
(symbol? 'a) -> true
(symbol? 'c) -> true
(pair? false) -> false
(pair? 1) -> false
(pair? 5) -> false
(pair? "string") -> false
(pair? (+ 1 2 3)) -> false
(pair? (not 1)) -> false
(pair? (cons 1 2)) -> true
(pair? (list 1 2 3)) -> true
(procedure? false) -> false
(procedure? 1) -> false
(procedure? 5) -> false
(procedure? "string") -> false
(procedure? (+ 1 2 3)) -> false
(procedure? (not 1)) -> false
(procedure? +) -> true
(procedure? -) -> true
(procedure? procedure?) -> true