type_="pie"
  
  Using <widget class_="chart" type_="pie"> produces a chart that
    displays each value in the given data set as a section of a circular pie, representing its
    percentage of the whole. (Available as of version 10.16)
Syntax
<dynamic>
    <widget class_="chart" type_="pie">
      [1010data_QUERY]
    </widget>
</dynamic>
      The [1010data_QUERY] associated with the widget should result in either a single numeric column or else a column of any type followed by one numeric column.
If the query results in a single numeric column, the row number is used as the category.
If the query results in a column of any type followed by one numeric column, the first column specifies the categories.
Example: type_="pie"
      
      The following example creates a chart widget that displays a pie chart.
        The pie chart is a graphical representation of the total sales by store in the table
          pub.demo.retail.item. A <graphspec> element is
        used to specify a title and its appearance as well as activating a tooltip when the mouse
        points to a slice of the pie.
<dynamic> <widget class_="chart" type_="pie" base_="pub.demo.retail.item" hints_="1"> <tabu label="Tabulation on Sales Item Detail" breaks="store"> <tcol fun="sum" source="sales" label="Sum of`Sales"/> </tabu> <graphspec> <title text="Total Sales by Store" color="darkgreen" font="24px sans-serif"> <margin left="-30"/> </title> <tooltip visible="true"/> </graphspec> </widget> </dynamic>

