Optimize is_protected_type slightly (used by force_text, which is used basically everywhere)

    return force_text(s, encoding, strings_only, errors)

_PROTECTED_TYPES = six.integer_types + (type(None), float, Decimal,

    datetime.datetime, datetime.date, datetime.time)

def is_protected_type(obj):

    """Determine if the object instance is of a protected type.

    Objects of protected types are preserved as-is when passed to

    force_text(strings_only=True).

    """

    return isinstance(obj, six.integer_types + (type(None), float, Decimal,

        datetime.datetime, datetime.date, datetime.time))

    return isinstance(obj, _PROTECTED_TYPES)

def force_text(s, encoding='utf-8', strings_only=False, errors='strict'):