<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _default_value_cell_data_func(self, tree_view_column, cell, model, iter, data=None):
 """Function set renderer properties for every single cell independently The function controls the editable and color scheme for every cell in the default value column according the use_runtime_value flag and whether the state is a library state. :param tree_view_column: the Gtk.TreeViewColumn to be rendered :param cell: the current CellRenderer :param model: the Gtk.ListStore or TreeStore that is the model for TreeView :param iter: an iterator over the rows of the TreeStore/Gtk.ListStore Model :param data: optional data to be passed: see http://dumbmatter.com/2012/02/some-notes-on-porting-from-pygtk-to-pygobject/ """

        if isinstance(self.model.state, LibraryState):
            use_runtime_value = model.get_value(iter, self.USE_RUNTIME_VALUE_STORAGE_ID)
            if use_runtime_value:
                cell.set_property("editable", True)
                cell.set_property('text', model.get_value(iter, self.RUNTIME_VALUE_STORAGE_ID))
                cell.set_property('foreground', "white")
            else:
                cell.set_property("editable", False)
                cell.set_property('text', model.get_value(iter, self.DEFAULT_VALUE_STORAGE_ID))
                cell.set_property('foreground', "dark grey")

        return