In this function call, `id` holds the identifier of the set for which the candidate
`geom` was sampled. Internally, the `EntityNetworkConstraintsMatrix` instance will
check `geom` against the other entity sets using all constraints that were defined for this identifier. For instance, in this example a disk-shaped geometry sampled from
the sampler with id `diskSetId`, will be checked against all entities of the set with
id `diskSetId` using `constraints1` and against all entities of the set with id `quadSetId`
using `constraintsOnOther`.
After successful generation of the desired number of entities, we again want to
construct an entity network from the raw entities and write it out in [Gmsh][1]
file format. In a first step, we again create an instance of the network builder
class for contained networks and define the sub-domains: