is_atomic, is_bare_atomic, is_bare_character, is_bare_double, is_bare_integer, is_bare_list, is_bare_logical, is_bare_numeric, is_bare_vector, is_character, is_double, is_empty, is_formula, is_function, is_integer, is_list, is_logical, is_null, is_scalar_atomic, is_scalar_character, is_scalar_double, is_scalar_integer, is_scalar_list, is_scalar_logical, is_scalar_vector, is_vector