Speed up your Python using Rust(developers.redhat.com)

    def count_doubles2(val):
        return sum(1 for c1, c2 in zip(val, val[1:]) if c1 == c2)

    In [56]: %timeit count_doubles(val)
    198 ms ± 13.8 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

    In [57]: %timeit count_doubles2(val)
    189 ms ± 21.1 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

    In [58]: %timeit sum(1 for c1, c2 in zip(val, val[1:]) if c1 == c2)
    135 ms ± 3.86 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

    In [59]: %timeit count_double_chars_np(val)
    6.95 ms ± 782 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

  PYBIND11_MODULE(_hll, m) {
      m.doc() = "pybind11-powered HyperLogLog"; // optional module docstring
      py::class_<hll_t> (m, "hll")
          .def(py::init<size_t>())
          .def("clear", &hll_t::clear, "Clear all entries.")
          .def("resize", &hll_t::resize, "Change old size to a new size.")
          .def("sum", &hll_t::sum, "Add up results.")
          .def("report", &hll_t::report, "Emit estimated cardinality. Performs sum if not performed, but sum must be recalculated if further entries are added.")
          .def("add", &hll_t::add, "Add a (hashed) value to the sketch.")
          .def("addh_", &hll_t::addh, "Hash an integer value and then add that to the sketch.");
  }