But === Assemble two meshes to form a new one. The two meshes to be assembled can come from operators: LIRE_MAILLAGE [:ref:`U4.21.01 `], [], DEFI_MAILLAGE [:ref:`U4.23.01 `], ASSE_MAILLAGE [:ref:`U4.23.03 `],... That is to say, they may contain ordinary meshes or supermeshes carrying macroelements. Produces a mesh-like data structure.