docs: def add_dependency(self,my_dep):
          """
          Adds a dependency to the dependency layer
          @type my_dep: L{Cdependency}
          @param my_dep: dependency object
          """
          if self.dependency_layer is None:
              self.dependency_layer = Cdependencies()
              self.root.append(self.dependency_layer.get_node())
          self.dependency_layer.add_dependency(my_dep)