Tweak formatting and docs for pretty printers
* python/libstdcxx/v6/printers.py (UniquePointerPrinter.to_string):
Remove redundant parentheses.
(RbtreeIterator, StdRbtreeIteratorPrinter): Add docstrings.
(StdForwardListPrinter.to_string): Remove redundant parentheses.
(StdExpOptionalPrinter.to_string): Use string formatting instead of
concatenation.
(StdVariantPrinter.to_string, StdNodeHandlePrinter.to_string)
(TemplateTypePrinter): Adjust whitespace.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@243689
138bc75d-0d04-0410-961f-
82ee72b054a4