Class URLError

Lib/urllib/error.py:19–32

class URLError(OSError):
    # URLError is a sub-type of OSError, but it doesn't share any of
    # the implementation. It overrides __init__ and __str__.
    # It sets self.args for compatibility with other OSError
    # subclasses, but args doesn't have the typical format with errno in
    # slot 0 and strerror in slot 1.  This may be better than nothing.
    def __init__(self, reason, filename=None):
        self.args = reason,
        self.reason = reason
        if filename is not None:
            self.filename = filename

    def __str__(self):
        return '<urlopen error %s>' % self.reason


class HTTPError(URLError, urllib.response.addinfourl):