MultiMethods with (class)name collision: add differences in the object states.
Exemple:
p = PAR(*[SelectKBest(k=k) for k in [1, 10, 100]]
[item.name for item in p.children]
Out[36]: ['SelectKBest(k=1)', 'SelectKBest(k=10)', 'SelectKBest(k=100)']