def merge_cells(start_row, start_col, end_row, end_col)
      validate_workbook

      self.merged_cells ||= RubyXL::MergedCells.new
      # TODO: add validation to make sure ranges are not intersecting with existing ones
      merged_cells << RubyXL::MergedCell.new(:ref => RubyXL::Reference.new(start_row, end_row, start_col, end_col))
    end
def merge_cells(start_row, start_col, end_row, end_col)
      validate_workbook

      self.merged_cells ||= RubyXL::MergedCells.new
      # TODO: add validation to make sure ranges are not intersecting with existing ones
      merged_cells << RubyXL::MergedCell.new(:ref => RubyXL::Reference.new(start_row, end_row, start_col, end_col))
    end
Merges cells within a rectangular area