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diff --git a/src/boost/libs/contract/example/n1962/equal.cpp b/src/boost/libs/contract/example/n1962/equal.cpp
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+++ b/src/boost/libs/contract/example/n1962/equal.cpp
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+
+// Copyright (C) 2008-2018 Lorenzo Caminiti
+// Distributed under the Boost Software License, Version 1.0 (see accompanying
+// file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
+// See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
+
+//[n1962_equal
+#include <boost/contract.hpp>
+#include <cassert>
+
+// Forward declaration because == and != contracts use one another's function.
+template<typename T>
+bool operator==(T const& left, T const& right);
+
+template<typename T>
+bool operator!=(T const& left, T const& right) {
+    bool result;
+    boost::contract::check c = boost::contract::function()
+        .postcondition([&] {
+            BOOST_CONTRACT_ASSERT(result == !(left == right));
+        })
+    ;
+
+    return result = (left.value != right.value);
+}
+
+template<typename T>
+bool operator==(T const& left, T const& right) {
+    bool result;
+    boost::contract::check c = boost::contract::function()
+        .postcondition([&] {
+            BOOST_CONTRACT_ASSERT(result == !(left != right));
+        })
+    ;
+
+    return result = (left.value == right.value);
+}
+
+struct number { int value; };
+
+int main() {
+    number n;
+    n.value = 123;
+
+    assert((n == n) == true);   // Explicitly call operator==.
+    assert((n != n) == false);  // Explicitly call operator!=.
+
+    return 0;
+}
+//]
+