 simple declarative API to easily get started.
                However, it does not bury the implementation in an abstraction layer that loses
                the major benefits of D3.
                Data sets can generally be provided as an array of objects, but no restriction is made on
                the format of the object.  Accessor functions can be defined to describe the shape and how
                to get what the chart needs from the data set, or to provide arbitrary logic to get the data
     