code: def clear_header_cols
        clear_header = @header_cols.select { |col| col !~ /^\(?c\d+[=~+]{,2}/ }
        if @sort
          clear_header.slice!(0, @sort.to_i) + clear_header.sort
        else
          clear_header
        end
      end
docs: Returns @header_cols without pattern. Will be sorted if sorted is not nil