instruction: What does below SAS code do
  PROC SUMMARY NWAY MISSING DATA=named_data;
  		CLASS col1 col2 col3 col4;
  		VAR tot_amt tot_gst_amt total_settlement_amt;
  		OUTPUT OUT=PYMT_SUM(DROP=_:) SUM=;
  	QUIT;
response: The SAS code block you provided uses the PROC SUMMARY procedure to calculate summary statistics for a dataset called named_data. Here's what each line of the code does:
  
  NWAY - specifies that the summary statistics should be calculated for all possible combinations of the CLASS variables.
  MISSING - specifies that missing values in the named_data dataset should be included in the summary statistics.
  CLASS - specifies the variables that define the groups for which the summary statistics should be calculated.
  VAR - specifies the variables for which summary statistics should be calculated.
  OUTPUT - specifies the output dataset and the statistics to include in the output.
  OUT - specifies the name of the output dataset.
  DROP=_: - drops the automatic variables created by SAS.
  SUM= - calculates the sum of the specified variables.
  The resulting output dataset PYMT_SUM will contain the summary statistics for each combination of the CLASS variables specified