typedef T1 int_type;The type is (typically) an integer type T1 that describes an object that can represent any element of the controlled
sequence as well as the value returned by eof(). It must be possible to type cast a value of type E to int_type then
back to E without altering the original value. In addition, the expression int_type('\0') must yield the code that
terminates a null-terminated string for elements of type E. Also, the expression int_type('\n') must yield a suitable
newline character of type E.