\begin{funcdesc}{intern}{string}

Enter \var{string} in the table of ``interned'' strings and return

the interned string -- which is \var{string} itself or a copy.

Interning strings is useful to gain a little performance on

dictionary lookup -- if the keys in a dictionary are interned, and

the lookup key is interned, the key comparisons (after hashing) can

be done by a pointer compare instead of a string compare. Normally,

the names used in Python programs are automatically interned, and

the dictionaries used to hold module, class or instance attributes

have interned keys. Interned strings are immortal (i.e. never get

garbage collected).

\end{funcdesc}