boltons should be builtins.
Boltons is a set of pure-Python utilities in the same spirit as — and yet conspicuously missing from — the the standard library, including:
Atomic file saving, bolted on with fileutils
A highly-optimized OrderedMultiDict, in dictutils
Two types of PriorityQueue, in queueutils
Chunked and windowed iteration, in iterutils
A full-featured TracebackInfo type, for representing stack traces, in tbutils
A lightweight UTC timezone available in timeutils.
Recursive mapping for nested data transforms, with remap