Construct a list from those elements of \var{list} for which
\var{function} returns true. \var{list} may be either a sequence, a
container which supports iteration, or an iterator, If \var{list}
- is a string (either \code{str} or \code{unicode}) or a tuple, the result
+ is a string or a tuple, the result
also has that type; otherwise it is always a list. If \var{function} is
\code{None}, the identity function is assumed, that is, all elements of
\var{list} that are false are removed.