docs: def find(self, other):
          """Return an interable of elements that overlap other in the tree."""
          iset = self._iset
          l = binsearch_left_start(iset, other[0] - self._maxlen, 0, len(iset))
          r = binsearch_right_end(iset, other[1], 0, len(iset))
          iopts = iset[l:r]
          iiter = (s for s in iopts if s[0] <= other[1] and s[1] >= other[0])
          for o in iiter: yield o