MAINT: Make no_default a sentinel value.
MAINT: Make no_default a sentinel value.

This prevents people from hitting it accidentally (you would have needed
to import it).

jdmcbr/toolz,pombredanne/toolz,quantopian/toolz,jcrist/toolz,machinelearningdeveloper/toolz,jdmcbr/toolz,machinelearningdeveloper/toolz,pombredanne/toolz,jcrist/toolz,quantopian/toolz