code: def init_sum_scheme(sum_scheme)
          row_scheme, col_scheme = sum_scheme.split(',') unless sum_scheme.nil?
  
          unless row_scheme.nil?
            @sum_row_title, @sum_row = row_scheme.split(':') unless row_scheme.empty?
          end
          
          @sum_row.nil? ? @sum_row = 0 : @sum_row = @sum_row.to_i
          @sum_row_title = 'Total' if @sum_row_title.nil? 
  
          col_scheme.nil? ? @sum_col_title = 'Total' : @sum_col_title = col_scheme
          @sum_col = 0
        end
docs: Initializes the sum row title an positions as well as the sum column
   title and position