sub can_set_value { 0 }
+sub aperture_for_set_value { [] }
+
sub action_for_set_value { undef }
sub can_add_member { 0 }
+sub aperture_for_add_member { [] }
+
sub action_for_add_member { undef }
+sub aperure_for_set_member { [] }
+
sub action_for_set_member { undef }
+sub aperture_for_remove_member { [] }
+
sub action_for_remove_member { undef }
sub specialize_for_member {