Prospectus excerpt:  We are offering 28,000,000 of our 7.600% Series E Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Units, liquidation preference $25.00 per unit (the “Series E Preferred Units”). Distributions on the Series E Preferred Units are cumulative from and including the date of original issue and will be payable quarterly in arrears on the 15th day of February, May, August and November of each year, commencing on August 15, 2019, in each case when, as, and if declared by our general partner. A pro-rated initial distribution on the Series E Preferred Units offered hereby will be payable on August 15, 2019 in an amount equal to approximately $0.58056 per Series E Preferred Unit. Distributions on the Series E Preferred Units will be payable out of amounts legally available therefor from and including the date of original issue to, but excluding, May 15, 2024, at a rate equal to 7.600% per annum of the stated liquidation preference. On and after May 15, 2024, distributions on the Series E Preferred Units will accumulate for each distribution period at a percentage of the $25.00 liquidation preference equal to an annual floating rate of the three-month LIBOR plus a spread of 5.161% per annum.