def tokenize(readline):
    """
    The tokenize() generator requires one argument, readline, which
    must be a callable object which provides the same interface as the
    readline() method of built-in file objects.  Each call to the function
    should return one line of input as bytes.  Alternatively, readline
    can be a callable function terminating with StopIteration:
        readline = open(myfile, 'rb').__next__  # Example of alternate readline

    The generator produces 5-tuples with these members: the token type; the
    token string; a 2-tuple (srow, scol) of ints specifying the row and
    column where the token begins in the source; a 2-tuple (erow, ecol) of
    ints specifying the row and column where the token ends in the source;
    and the line on which the token was found.  The line passed is the
    logical line; continuation lines are included.

    The first token sequence will always be an ENCODING token
    which tells you which encoding was used to decode the bytes stream.
    """
    # This import is here to avoid problems when the itertools module is not
    # built yet and tokenize is imported.
    from itertools import chain, repeat
    encoding, consumed = detect_encoding(readline)
    rl_gen = iter(readline, b"")
    empty = repeat(b"")
    return _tokenize(chain(consumed, rl_gen, empty).__next__, encoding)