@Override
    public StreamFunction visitStream_function(@NotNull SiddhiQLParser.Stream_functionContext ctx) {

        AttributeFunction attributeFunction = (AttributeFunction) visit(ctx.function_operation());
        StreamFunction streamFunction = new StreamFunction(attributeFunction.getNamespace(),
                attributeFunction.getName(), attributeFunction.getParameters());
        populateQueryContext(streamFunction, ctx);
        return streamFunction;
    }
{@inheritDoc}
<p>The default implementation returns the result of calling
{@link #visitChildren} on {@code ctx}.</p>

@param ctx
modules/siddhi-query-compiler/src/main/java/io/siddhi/query/compiler/internal/SiddhiQLBaseVisitorImpl.java