gap between soma and non-soma branches

[danilobenozzo]

example with a Purkinje cell:

1. soma at point 21 (see PC .swc file and image attached) has the dendrite attached (only one) which starts from point 40
   after creating the cell PCcell:

from arborize import bsb_schematic
from arborize import neuron_build
from bsb.morphologies import Morphology 
from dbbs_models import PurkinjeCellmodel

morpho = Morphology.from_swc(file_morphology, tags=PurkinjeCellmodel.swc_tags)
schematic = bsb_schematic(morpho, PurkinjeCellmodel)
PCcell = neuron_build(schematic)

>>> PCcell.soma[1].children()[0].psection()['morphology']['pts3d']
[(-10.5770263671875, 7.5341033935546875, 0.0, 3.6700000762939453),
 (-9.3170166015625, 12.0941162109375, 0.0, 3.6700000762939453)]

note that first row is not the parent point coordinate xyz, it starts directly from point 40 => it allows gap and this is ok when connecting soma with non-soma branches;

2. by adding a second child to point 2:

>>> PCcell.soma[1].children()[0].psection()['morphology']['pts3d']
[(-19.92120361328125, 1.2533416748046875, 0.0, 4.665064811706543),
 (-15.0, 7.0, 0.0, 3.6700000762939453),
 (-20.0, 7.0, 0.0, 3.6700000762939453)]

it added in the first row the parent coordinate, thus it fills the gap (which means also making the branch longer)