# Help with partitioning an interval for Riemann integral of piecewise function

If $$f(x)= \begin{cases} x &-1 then prove $$f$$ is integrable on $$[-1,1]$$

I am studying this topic, and my textbook has no example how to partition a piecewise function. I know the formulas for lower sums and upper sums, but I need some help with partitioning and deciding for component intervals, please.