'lower_bound()' iterates between param #1 and param #2, comparing the result
with param #3 - either by making the comparison internally or by deferring to
an external comparator function. Prior to C99 however, BOTH cases required
param #3 to match the type being iterated.
In the case of a deferred comparison, there was apparently a proposal to
relax this restriction in C99, though I'm not sure if it in fact got
implemented (can't find any examples of it anywhere...)
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