+// For backward compatibility, this header includes
+// <boost/bind/bind.hpp> and then imports the placeholders _1, _2,
+// _3, ... into the global namespace. Definitions in the global
+// namespace are not a good practice and this use is deprecated.
+// Please switch to including <boost/bind/bind.hpp> directly,
+// adding the using directive locally where appropriate.
+// Alternatively, the existing behavior may be preserved by defining
+// the macro BOOST_BIND_GLOBAL_PLACEHOLDERS.