r = r[:-6] + 'Z'

        return r

    elif isinstance(obj, datetime.date):

        return obj.isoformat()

    elif isinstance(obj, decimal.Decimal):

        return str(obj)

    elif isinstance(obj, datetime.time):

        if _is_aware(obj):

            raise ValueError("JSON can't represent timezone-aware times.")

        r = obj.isoformat()

        if obj.microsecond:

            r = r[:12]

        return r

    elif isinstance(obj, set):

        return list(obj)

    elif hasattr(obj, '__json__'):

        if callable(obj.__json__):

            return obj.__json__()

        else:

            return obj.__json__

    else:

        raise NotImplementedError

# Import simplejson

try:

    # import simplejson initially

    import simplejson as _sj

    def extended_encode(obj):

        try:

            return _obj_dump(obj)

        except NotImplementedError:

            pass

        raise TypeError("%r is not JSON serializable" % (obj,))

    # we handle decimals our own it makes unified behavior of json vs

    # simplejson

    _sj.dumps = functools.partial(_sj.dumps, default=extended_encode,

                                  use_decimal=False)

    _sj.dump = functools.partial(_sj.dump, default=extended_encode,

                                 use_decimal=False)

    simplejson = _sj

except ImportError:

    # no simplejson set it to None

    _sj = None

# simplejson not found try out regular json module

import json as _json

# extended JSON encoder for json

class ExtendedEncoder(_json.JSONEncoder):

    def default(self, obj):

        try:

            return _obj_dump(obj)

        except NotImplementedError:

            pass

        return _json.JSONEncoder.default(self, obj)

# monkey-patch JSON encoder to use extended version

_json.dumps = functools.partial(_json.dumps, cls=ExtendedEncoder)

_json.dump = functools.partial(_json.dump, cls=ExtendedEncoder)

stdlib = _json

# set all available json modules

simplejson = _sj

stdjson = _json

json = _sj if _sj else _json