For this problem, we'll use a small subset of the ICDB quality of life data. The permanent SAS data sets qul11 and qul21 each contain five variables: subj_id, the subject's id number v_type, the visit type which should be 0 for each subject in the data set v_date, the date the form was completed qul_1, the subject's reply to the first answer on the quality of life form qul_2, the subject's reply to the second answer on the quality of life form The data set qul11 contains 106 observations on only those subjects whose id number starts with 11. The data set qul21 contains 109 observations on only those subjects whose id number starts with 21. Do what it takes to concatenate the two data sets into one temporary data set named qul containing 215 observations. For output, rather than printing the entire data set, just use PROC CONTENTS to report the structure and contents of the qul data set.