How to use the acme.jose.errors function in acme

def fields_to_partial_json(self):
        """Serialize fields to JSON."""
        jobj = {}
        omitted = set()
        for slot, field in six.iteritems(self._fields):
            value = getattr(self, slot)

            if field.omit(value):
                omitted.add((slot, value))
            else:
                try:
                    jobj[field.json_name] = field.encode(value)
                except errors.SerializationError as error:
                    raise errors.SerializationError(
                        'Could not encode {0} ({1}): {2}'.format(
                            slot, value, error))
        if omitted:
            # pylint: disable=star-args
            logger.debug('Omitted empty fields: %s', ', '.join(
                '{0!s}={1!r}'.format(*field) for field in omitted))
        return jobj

def _decode_param(cls, data):
        """Decode Base64urlUInt."""
        try:
            return int(binascii.hexlify(json_util.decode_b64jose(data)), 16)
        except ValueError:  # invalid literal for long() with base 16
            raise errors.DeserializationError()

def json_loads(cls, json_string):
        """Deserialize from JSON document string."""
        try:
            loads = json.loads(json_string)
        except ValueError as error:
            raise errors.DeserializationError(error)
        return cls.from_json(loads)

def encode(self, name):
        """Encode a single field.

        :param str name: Name of the field to be encoded.

        :raises errors.SerializationError: if field cannot be serialized
        :raises errors.Error: if field could not be found

        """
        try:
            field = self._fields[name]
        except KeyError:
            raise errors.Error("Field not found: {0}".format(name))

        return field.encode(getattr(self, name))

# so that, e.g Revocation.from_json(jobj) fails if
            # jobj["type"] != "revocation".
            return cls

        if not isinstance(jobj, dict):
            raise errors.DeserializationError(
                "{0} is not a dictionary object".format(jobj))
        try:
            typ = jobj[cls.type_field_name]
        except KeyError:
            raise errors.DeserializationError("missing type field")

        try:
            return cls.TYPES[typ]
        except KeyError:
            raise errors.UnrecognizedTypeError(typ, jobj)

def sign(self, key, msg):
        """Sign the ``msg`` using ``key``."""
        try:
            signer = key.signer(self.padding, self.hash)
        except AttributeError as error:
            logger.debug(error, exc_info=True)
            raise errors.Error("Public key cannot be used for signing")
        except ValueError as error:  # digest too large
            logger.debug(error, exc_info=True)
            raise errors.Error(str(error))
        signer.update(msg)
        try:
            return signer.finalize()
        except ValueError as error:
            logger.debug(error, exc_info=True)
            raise errors.Error(str(error))

return loader(data, password, backend)
            except (ValueError, TypeError,
                    cryptography.exceptions.UnsupportedAlgorithm) as error:
                exceptions[loader] = error

        # public key?
        for loader in (serialization.load_pem_public_key,
                       serialization.load_der_public_key):
            try:
                return loader(data, backend)
            except (ValueError,
                    cryptography.exceptions.UnsupportedAlgorithm) as error:
                exceptions[loader] = error

        # no luck
        raise errors.Error('Unable to deserialize key: {0}'.format(exceptions))

def json_loads(cls, json_string):
        """Deserialize from JSON document string."""
        try:
            loads = json.loads(json_string)
        except ValueError as error:
            raise errors.DeserializationError(error)
        return cls.from_json(loads)

# so that, e.g Revocation.from_json(jobj) fails if
            # jobj["type"] != "revocation".
            return cls

        if not isinstance(jobj, dict):
            raise errors.DeserializationError(
                "{0} is not a dictionary object".format(jobj))
        try:
            typ = jobj[cls.type_field_name]
        except KeyError:
            raise errors.DeserializationError("missing type field")

        try:
            return cls.TYPES[typ]
        except KeyError:
            raise errors.UnrecognizedTypeError(typ, jobj)