Add get_mesh:Vh->mesh function to the language

It allows to get the mesh that carries a discrete function

src/language/modules/SchemeModule.cpp

@@ -731,6 +731,20 @@ SchemeModule::SchemeModule()
 
                                                    ));
 
+  this->_addBuiltinFunction("get_mesh",
+                            std::function(
+
+                              [](const std::shared_ptr<const DiscreteFunctionVariant>& discrete_function_variant)
+                                -> std::shared_ptr<const MeshVariant> {
+                                return std::visit(   //
+                                  [](auto&& discrete_function) {
+                                    return discrete_function.meshVariant();   //
+                                  },
+                                  discrete_function_variant->discreteFunction());
+                              }
+
+                              ));
+
   MathFunctionRegisterForVh{*this};
 }