How to use the fastavro.io.symbols.Sequence function in fastavro

def _parse(self, schema):
        record_type = extract_record_type(schema)

        if record_type == 'record':
            production = []

            production.append(RecordStart())
            for field in schema["fields"]:
                production.insert(0, FieldStart(field["name"]))
                production.insert(0, self._parse(field["type"]))
                production.insert(0, FieldEnd())
            production.insert(0, RecordEnd())

            seq = Sequence(*production)
            return seq

        elif record_type == 'union':
            symbols = []
            labels = []
            for candidate_schema in schema:
                symbols.append(self._parse(candidate_schema))
                if isinstance(candidate_schema, dict):
                    labels.append(
                        candidate_schema.get(
                            "name",
                            candidate_schema.get("type")
                        )
                    )
                else:
                    labels.append(candidate_schema)

self._parse(schema["values"]),
                MapKeyMarker(),
                String(),
            )
            return Sequence(repeat, MapStart())

        elif record_type == "array":
            repeat = Repeater(
                ArrayEnd(),
                ItemEnd(),
                self._parse(schema["items"]),
            )
            return Sequence(repeat, ArrayStart())

        elif record_type == "enum":
            return Sequence(EnumLabels(schema["symbols"]), Enum())

        elif record_type == "null":
            return Null()
        elif record_type == "boolean":
            return Boolean()
        elif record_type == "string":
            return String()
        elif record_type == "bytes":
            return Bytes()
        elif record_type == "int":
            return Int()
        elif record_type == "long":
            return Long()
        elif record_type == "float":
            return Float()
        elif record_type == "double":

)
                    )
                else:
                    labels.append(candidate_schema)

            return Sequence(Alternative(symbols, labels), Union())

        elif record_type == "map":
            repeat = Repeater(
                MapEnd(),
                # ItemEnd(),  # TODO: Maybe need this?
                self._parse(schema["values"]),
                MapKeyMarker(),
                String(),
            )
            return Sequence(repeat, MapStart())

        elif record_type == "array":
            repeat = Repeater(
                ArrayEnd(),
                ItemEnd(),
                self._parse(schema["items"]),
            )
            return Sequence(repeat, ArrayStart())

        elif record_type == "enum":
            return Sequence(EnumLabels(schema["symbols"]), Enum())

        elif record_type == "null":
            return Null()
        elif record_type == "boolean":
            return Boolean()

repeat = Repeater(
                MapEnd(),
                # ItemEnd(),  # TODO: Maybe need this?
                self._parse(schema["values"]),
                MapKeyMarker(),
                String(),
            )
            return Sequence(repeat, MapStart())

        elif record_type == "array":
            repeat = Repeater(
                ArrayEnd(),
                ItemEnd(),
                self._parse(schema["items"]),
            )
            return Sequence(repeat, ArrayStart())

        elif record_type == "enum":
            return Sequence(EnumLabels(schema["symbols"]), Enum())

        elif record_type == "null":
            return Null()
        elif record_type == "boolean":
            return Boolean()
        elif record_type == "string":
            return String()
        elif record_type == "bytes":
            return Bytes()
        elif record_type == "int":
            return Int()
        elif record_type == "long":
            return Long()