Several STLs to OBJ with groups (and also export vector normals?)

[otaolafranc]

Hello,
I am looking to imitate the files that is created in blender when I import several STLs, select all of them and export them in one obj file. it will create a group for each stl and also add the vector normal. when I export using meshio doing:

M=meshio.read('file.stl',file_format='stl')
M.write('file.obj',file_format='obj')

the 'file.stl' is a concatenation of the different STLs (using cat *.stl >file.stl) that I import into blender.
is there any way to do what I am looking to do in meshio itself?