message: Combine some aggregation examples
diff: Table.join [item_names, num_transactions, num_sold]
  > Example
  - Compute the maximum value of a column.
  + Compute the maximum value of a column, the minimum value, the sum of its
  + values, and its mean, and return these in a vector.
  import Standard.Examples
  - example_max = Examples.integer_column.max
  + example_aggregate =
  + column = Examples.integer_column
  + max = column.max
  + min = column.min
  + sum = column.sum
  + mean = column.mean
  + [max, min, sum, mean]
  - > Example
  - Sum the values in a column.
  -
  - import Standard.Examples
  -
  - example_sum = Examples.integer_column.sum
  -
  - > Example
  - Compute the mean value of a column.
  -
  - import Standard.Examples
  -
  - example_mean = Examples.integer_column.mean
  