def column(index)
      index = parse_index(index)
      columns = []
      @data.each do |row|
        columns << row_to_array(row)[index].value
      end
      columns
    end
def column(index)
      index = parse_index(index)
      columns = []
      @data.each do |row|
        columns << row_to_array(row)[index].value
      end
      columns
    end
Retrieves the column at the given index. Aliases can be used