Ceate a set (type?) of list of integers that varies at run time

[Mace Ayres <mace.ayres@gmail.com>]

* Using the word set in mathetical sense.
I have an array 2D_array is Integer 1..9, 1..9 of my_record.  — my_record has a boolean field locked.
Before looping/iteration across 2D_array (r,c), I want to restrict the columns (c) that I process, to bet something  like
for r in 1..9 loop
 for c (column) in (columns_to_check)

I have to create the enumeration type? list of columns to check and put in my columns_to_check container
and then only iterate these, maybe 1,2,3,7,8,9 — do not check 4,5 or 6

Need a function like get_columns_to_check
that iterates all 1..9 columns 
if (r,c).locked is true 
then do not have in final columns_to_check something (range, or enumeration type)
either add to empty columns_to_check or delete from default columns_to_check that has 1..9;

what kind, type of an object can I use to hold the valid columns to check thing-e columns_to_check
and that I can also iterate across.

Can I have a range that is not a continuous series of integers, NOT 1..9 but 1,2,5,6,7,9 
and then some different subset of 1..9 the next time. Recalculating a new set Columns_to_check for each outer loop of rows?

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