sage: Family?

String Form:    <function Family at 0x92abe64>
Namespace:      Interactive
Loaded File:    /home/darij/sage-5.6/local/lib/python2.7/site-packages/sage/sets/family.py
Source File:    /home/darij/sage-5.6/devel/sage/sage/sets/family.py
Definition:     Family(indices, function=None, hidden_keys=[], hidden_function=None, lazy=False, name=None)
Docstring:
       A Family is an associative container which models a family (f_i)_{i
       in I}. Then, f[i] returns the element of the family indexed by i.
       Whenever available, set and combinatorial class operations
       (counting, iteration, listing) on the family are induced from those
       of the index set.
    
       There are several available implementations (classes) for different
       usages; Family serves as a factory, and will create instances of
       the appropriate classes depending on its arguments.
    
       EXAMPLES:
    
       In its simplest form, a list l or a tuple by itself is considered
       as the family (l[i]_{i in I}) where I is the range 0...,len(l).
       So Family(l) returns the corresponding family:

       value (ie: "False" for finite data structures and "True" for
       enumerated sets: