Create a line chart based on field values in case of One2Many

Sir, can u provide me the reference where the code for graph view written in any of tryton module for the above mentioned topic is provided.

Any help regarding this will be appreciable.

There is an example on the stock module, on the quantities by warehouse graph

How to plot DateTime field on x axis and other outputs in y axis like y1, y2, y3 etc but we need to filter them like x and y1 as a single graph from the combined graph of x axis as datetime field and y1, y2 and y3 as outputs.