This example shows a very short parent segment with a fine discretization
joined to two daughter segments 
In the morphology, the daughters are specified as starting from the end 
of the parent segment each with their own radius but not with an exact 
position. 
When discretized, the daughters should be offset so as not to overlap, 
and should connect to the right parts of the parent disk. 
Initially, the only non-zero concentrations are in one of the daughter
segments, but these should diffuse into the disk and thin into the other 
daughter.
 