How to use the feast.entity.Entity function in feast

def test_all_types_register_feature_set_success(client):
    all_types_fs_expected = FeatureSet(
        name="all_types",
        entities=[Entity(name="user_id", dtype=ValueType.INT64)],
        features=[
            Feature(name="float_feature", dtype=ValueType.FLOAT),
            Feature(name="int64_feature", dtype=ValueType.INT64),
            Feature(name="int32_feature", dtype=ValueType.INT32),
            Feature(name="string_feature", dtype=ValueType.STRING),
            Feature(name="bytes_feature", dtype=ValueType.BYTES),
            Feature(name="bool_feature", dtype=ValueType.BOOL),
            Feature(name="double_feature", dtype=ValueType.DOUBLE),
            Feature(name="double_list_feature", dtype=ValueType.DOUBLE_LIST),
            Feature(name="float_list_feature", dtype=ValueType.FLOAT_LIST),
            Feature(name="int64_list_feature", dtype=ValueType.INT64_LIST),
            Feature(name="int32_list_feature", dtype=ValueType.INT32_LIST),
            Feature(name="string_list_feature",
                    dtype=ValueType.STRING_LIST),
            Feature(name="bytes_list_feature", dtype=ValueType.BYTES_LIST),
        ],

entities=[Entity("entity_id", ValueType.INT64)],
            max_age=Duration(seconds=100),
        )
    client.apply(historical_fs)

    fs1 = FeatureSet(
            "feature_set_1",
            features=[Feature("feature_value6", ValueType.STRING)],
            entities=[Entity("entity_id", ValueType.INT64)],
            max_age=Duration(seconds=100),
        )

    fs2 = FeatureSet(
        "feature_set_2",
        features=[Feature("other_feature_value7", ValueType.INT64)],
        entities=[Entity("other_entity_id", ValueType.INT64)],
        max_age=Duration(seconds=100),
    )
    client.apply(fs1)
    client.apply(fs2)

max_age=Duration(seconds=100),
        )
    client.apply(file_fs1)

    gcs_fs1 = FeatureSet(
            "gcs_feature_set",
            features=[Feature("feature_value2", ValueType.STRING)],
            entities=[Entity("entity_id", ValueType.INT64)],
            max_age=Duration(seconds=100),
        )
    client.apply(gcs_fs1)

    proc_time_fs = FeatureSet(
            "processing_time",
            features=[Feature("feature_value3", ValueType.STRING)],
            entities=[Entity("entity_id", ValueType.INT64)],
            max_age=Duration(seconds=100),
        )
    client.apply(proc_time_fs)

    add_cols_fs = FeatureSet(
            "additional_columns",
            features=[Feature("feature_value4", ValueType.STRING)],
            entities=[Entity("entity_id", ValueType.INT64)],
            max_age=Duration(seconds=100),
        )
    client.apply(add_cols_fs)

    historical_fs = FeatureSet(
            "historical",
            features=[Feature("feature_value5", ValueType.STRING)],
            entities=[Entity("entity_id", ValueType.INT64)],

def entities(self) -> List[Entity]:
        """
        Returns list of entities from this feature set
        """
        return [field for field in self._fields.values() if isinstance(field, Entity)]

def entities(self, entities: List[Entity]):
        """
        Sets the active entities within this feature set

        Args:
            entities: List of entities objects
        """
        for entity in entities:
            if not isinstance(entity, Entity):
                raise Exception("object type is not na Entity: " + str(type(entity)))

        for key in list(self._fields.keys()):
            if isinstance(self._fields[key], Entity):
                del self._fields[key]

        if entities is not None:
            self._add_fields(entities)