code: def visit(self, node):
          
          old_omp = metadata.get(node, OMPDirective)
          node = super(DeadCodeElimination, self).visit(node)
          if not metadata.get(node, OMPDirective):
              for omp_directive in old_omp:
                  metadata.add(node, omp_directive)
          return node
docs: Add OMPDirective from the old node to the new one.