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diff --git a/src/boost/libs/histogram/examples/guide_histogram_reduction.cpp b/src/boost/libs/histogram/examples/guide_histogram_reduction.cpp
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+++ b/src/boost/libs/histogram/examples/guide_histogram_reduction.cpp
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+// Copyright 2015-2018 Hans Dembinski
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+//[ guide_histogram_reduction
+
+#include <boost/histogram.hpp>
+#include <cassert>
+
+int main() {
+  using namespace boost::histogram;
+
+  // make a 2d histogram
+  auto h = make_histogram(axis::regular<>(4, 0.0, 4.0), axis::regular<>(4, -1.0, 1.0));
+
+  h(0, -0.9);
+  h(1, 0.9);
+  h(2, 0.1);
+  h(3, 0.1);
+
+  // shrink the first axis to remove the highest bin
+  // rebin the second axis by merging pairs of adjacent bins
+  auto h2 = algorithm::reduce(h, algorithm::shrink(0, 0.0, 3.0), algorithm::rebin(1, 2));
+
+  assert(h2.axis(0).size() == 3);
+  assert(h2.axis(0).bin(0).lower() == 0.0);
+  assert(h2.axis(0).bin(2).upper() == 3.0);
+  assert(h2.axis(1).size() == 2);
+  assert(h2.axis(1).bin(0).lower() == -1.0);
+  assert(h2.axis(1).bin(1).upper() == 1.0);
+
+  // reduce does not change the total count if the histogram has underflow/overflow bins;
+  // counts in removed bins are added to the corresponding under- and overflow bins
+  assert(algorithm::sum(h) == 4 && algorithm::sum(h2) == 4);
+}
+
+//]