Is there a python GMSH function that can transform a 2.2 .msh file to a 4.1 .msh file?

Question

Because of the software used in my project, I would need to 'translate' a GMSH .msh file generated in version 2.2 into a version 4.1 .msh file using the Python GMSH library.

I tried merging the 2.2 msh file into a gmsh model, then setting the version to 4.1 before writing a new file, with the following:

print("Using GMSH to get from GMSH 2.2 .msh to GMSH 4.1 .msh")
gmsh.initialize()
gmsh.option.setNumber("Mesh.MshFileVersion", 2.2)
gmsh.merge("./01_Mesh/{}_gmsh2.msh".format(file_name))
gmsh.model.add("gmsh_mesh")
gmsh.option.setNumber("Mesh.MshFileVersion", 4.1)
gmsh.write("./01_Mesh/{}_gmsh4.msh".format(file_name))
if '-nopopup' not in sys.argv:
    gmsh.fltk.run()
gmsh.finalize()

However, this saves an empty file. Does anyone know how to fix this please?