Builds the layer for one graph series.
A link whose ends cannot both be named is dropped: a flow needs both to be a flow at all, and half of one is not a reading.
The series to read
The layer, or undefined when the series carries no links
undefined
Builds the layer for one graph series.
A link whose ends cannot both be named is dropped: a flow needs both to be a flow at all, and half of one is not a reading.