Yield pep8 error codes that autopep8 fixes.

    Each item we yield is a tuple of the code followed by its
    description.

def supported_fixes():
    """Yield pep8 error codes that autopep8 fixes.

    Each item we yield is a tuple of the code followed by its
    description.

    """
    yield ('E101', docstring_summary(reindent.__doc__))

    instance = FixPEP8(filename=None, options=None, contents='')
    for attribute in dir(instance):
        code = re.match('fix_([ew][0-9][0-9][0-9])', attribute)
        if code:
            yield (
                code.group(1).upper(),
                re.sub(r'\s+', ' ',
                       docstring_summary(getattr(instance, attribute).__doc__))
            )

    for (code, function) in sorted(global_fixes()):
        yield (code.upper() + (4 - len(code)) * ' ',
               re.sub(r'\s+', ' ', docstring_summary(function.__doc__)))

    for code in sorted(CODE_TO_2TO3):
        yield (code.upper() + (4 - len(code)) * ' ',
               re.sub(r'\s+', ' ', docstring_summary(fix_2to3.__doc__)))