| 
 | 4.10 list
Lists are arrays whose elements can be of different types (including ring).
If one element belongs to a ring the whole list belongs to that
ring. This applies also to the special list  
Note that a list stores the objects itself and not the names.  Hence, if
 Note: Unlike other assignments a ring as an element of a list is not a copy but another reference to the same ring. 
 
 | 
|   |  |  |  |  |  |  |  |  |  |