Argument dependent lookup deduces the Dune namespace from the function arguments that are also in namespace Dune.
see https://www.dune-project.org/doc/doxygen/html/group__GIIteration.html
Argument dependent lookup deduces the Dune namespace from the function arguments that are also in namespace Dune.
see https://www.dune-project.org/doc/doxygen/html/group__GIIteration.html