def render
      buffer = []
      _guess_col_widths
      rows = @list.size.to_s.length
      @rows = rows
      _prepare_format
      
      str = ""
      if @numbering
        str = " "*(rows+1)+@y
      end
      str <<  @fmstr % @columns
      buffer << str
      #puts "-" * str.length
      buffer << separator
      if @list
        if @numbering
          @fmstr = "%#{rows}d "+ @y + @fmstr
        end
        #@list.each { |e| puts e.join(@y) }
        count = 0
        @list.each_with_index { |r,i|  
          value = convert_value_to_text r, count
          buffer << value
          count += 1
        }
      end
      buffer
    end
def render
      buffer = []
      _guess_col_widths
      rows = @list.size.to_s.length
      @rows = rows
      _prepare_format
      
      str = ""
      if @numbering
        str = " "*(rows+1)+@y
      end
      str <<  @fmstr % @columns
      buffer << str
      #puts "-" * str.length
      buffer << separator
      if @list
        if @numbering
          @fmstr = "%#{rows}d "+ @y + @fmstr
        end
        #@list.each { |e| puts e.join(@y) }
        count = 0
        @list.each_with_index { |r,i|  
          value = convert_value_to_text r, count
          buffer << value
          count += 1
        }
      end
      buffer
    end
Now returns an array with formatted data
 @return [Array<String>] array of formatted data