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* The selector factories k_(), a_() and m_() have much faster implementations
because they are now simply aliases for itemgetter, attrgetter and
methodcaller from the Python standard library operator module. As a
result, even though they remain backwards API compatible with those in
asq 1.0 their capabilities are also extended somewhat:
* k_ can optionally accept more than one argument (key) and if so, the
selector it produces will return a tuple of multiple looked-up values
rather than a single value.
* a_ can optionally accept more than one argument (key) and if so, the
selector it produces will return a tuple of multiple looked-up values
rather than a single value. Furthermore, the attribute names supplied
in each argument can now contain dots to refer to nested attributes.
* Added asq.selectors.make_selector which will create a selector directly
from a string or integer using attribute or item lookup respectively.