Dear all,

I am using gmsh to build a geometry.

This geometry is composed by several simple subdomains (for example boxes), so I was thinking on defining each of them separately and then use the boolean operation `gmsh.model.occ.fuse`

.

However, it seems that it is only allowed to fuse two geometries (and not three or more). For example, if we consider the following minimal example (fusing three simple boxes):

```
# Initialise meshing process
import gmsh
gmsh.initialize()
# Subdomains
box1 = gmsh.model.occ.addBox(-1.5, -0.5, 0, 1, 1, 1)
box2 = gmsh.model.occ.addBox(-0.5, -0.5, 0, 1, 1, 1)
box3 = gmsh.model.occ.addBox(0.5, -0.5, 0, 1, 1, 1)
# Fuse subdomains into a single domain
gmsh.model.occ.fuse([(3,box1)], [(3,box2)], [(3,box3)])
```

I get an error in the last line.

Is there an alternative way of performing this operation? I know that a solution would be to define each surface of the final domain, but fusing geometries would be much simpler for my real geometry.

Many thanks in advance.