delete_if (FasterCSV::Table)

    # File lib/faster_csv.rb, line 650
        def delete_if(&block)
          if @mode == :row or @mode == :col_or_row  # by index
            @table.delete_if(&block)
          else                                      # by header
            to_delete = Array.new
            headers.each_with_index do |header, i|
              to_delete << header if block[[header, self[header]]]
            end
            to_delete.map { |header| delete(header) }
          end

          self  # for chaining
        end