nesting.

        width
            Attempted maximum number of columns in the output.

        depth
            The maximum depth to print out nested structures.

        stream
            The desired output stream.  If omitted (or false), the standard
            output stream available at construction will be used.

        compact
            If true, several items will be combined in one line.

        sort_dicts
            If true, dict keys are sorted.

        r