feat: new mf_increment macro

all.sas

@@ -1598,6 +1598,35 @@ Usage:
   &engine
 
 %mend mf_getxengine;
+/**
+  @file
+  @brief Increments a macro variable
+  @details Useful outside of do-loops - will increment a macro variable every
+  time it is called.
+
+  Example:
+
+      %let cnt=1;
+      %put We have run %mf_increment(cnt) lines;
+      %put Now we have run %mf_increment(cnt) lines;
+      %put There are %mf_increment(cnt) lines in total;
+
+  @param [in] MACRO_NAME the name of the macro variable to increment
+  @param [in] ITER= The amount to add or subtract to the macro
+
+  <h4> Related Files </h4>
+  @li mf_increment.test.sas
+
+**/
+
+%macro mf_increment(macro_name,incr=1);
+
+  /* iterate the value */
+  %let &macro_name=%eval(&&&macro_name+&incr);
+  /* return the value */
+  &&&macro_name
+
+%mend mf_increment;
 /**
   @file mf_isblank.sas
   @brief Checks whether a macro variable is empty (blank)