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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_avatar_url(self, size=2):
 """Get URL to avatar picture :param size: possible values are ``0``, ``1``, or ``2`` corresponding to small, medium, large :type size: :class:`int` :return: url to avatar :rtype: :class:`str` """

        hashbytes = self.get_ps('avatar_hash')

        if hashbytes != "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000":
            ahash = hexlify(hashbytes).decode('ascii')
        else:
            ahash = 'fef49e7fa7e1997310d705b2a6158ff8dc1cdfeb'

        sizes = {
            0: '',
            1: '_medium',
            2: '_full',
        }
        url = "http://cdn.akamai.steamstatic.com/steamcommunity/public/images/avatars/%s/%s%s.jpg"

        return url % (ahash[:2], ahash, sizes[size])