def prepare_tables(table_id)
      if tables_count > 0
        id = table_id
        tables.each do |table|
          table.prepare(id)

          # Store the link used for the rels file.
          @external_table_links << ['/table', "../tables/table#{id}.xml"]
          id += 1
        end
      end
      tables_count || 0
    end
def prepare_tables(table_id)
      if tables_count > 0
        id = table_id
        tables.each do |table|
          table.prepare(id)

          # Store the link used for the rels file.
          @external_table_links << ['/table', "../tables/table#{id}.xml"]
          id += 1
        end
      end
      tables_count || 0
    end
Set the table ids for the worksheet tables.