class PgBackendPidFunction extends Scalar<Integer, Void> {

    public static final String NAME = "pg_backend_pid";
    private static final FunctionName FQN = new FunctionName(PgCatalogSchemaInfo.NAME, NAME);

    public static void register(Functions.Builder module) {
        module.add(
            scalar(
                FQN,
                DataTypes.INTEGER.getTypeSignature()
            ).withFeatures(EnumSet.of(Feature.NON_NULLABLE)),
            PgBackendPidFunction::new
        );
    }

    public PgBackendPidFunction(Signature signature, BoundSignature boundSignature) {
        super(signature, boundSignature);
    }

    @Override
    public Symbol normalizeSymbol(Function symbol, TransactionContext txnCtx, NodeContext nodeCtx) {<FILL_FUNCTION_BODY>}

    @Override
    public Integer evaluate(TransactionContext txnCtx, NodeContext nodeCtx, Input[] args) {
        assert args.length == 0 : "number of args must be 0";
        return -1;
    }
}

        assert symbol.arguments().size() == 0 : "function's number of arguments must be 0";
        return Literal.of(-1);
    
<methods>public BoundSignature boundSignature() ,public Scalar<java.lang.Integer,java.lang.Void> compile(List<io.crate.expression.symbol.Symbol>, java.lang.String, io.crate.role.Roles) ,public transient abstract java.lang.Integer evaluate(io.crate.metadata.TransactionContext, io.crate.metadata.NodeContext, Input<java.lang.Void>[]) ,public io.crate.expression.symbol.Symbol normalizeSymbol(io.crate.expression.symbol.Function, io.crate.metadata.TransactionContext, io.crate.metadata.NodeContext) ,public io.crate.metadata.functions.Signature signature() <variables>public static final Set<io.crate.metadata.Scalar.Feature> DETERMINISTIC_AND_COMPARISON_REPLACEMENT,public static final Set<io.crate.metadata.Scalar.Feature> DETERMINISTIC_ONLY,public static final Set<io.crate.metadata.Scalar.Feature> NO_FEATURES,protected final non-sealed BoundSignature boundSignature,protected final non-sealed io.crate.metadata.functions.Signature signature