https://www.boost.org/doc/libs/master/doc/html/doxygen/headers/user__macros_8hpp_1a41bd0e25eb1c4ebec282e3d444a15e66.html
Macro BOOST_YAP_USER_LITERAL_PLACEHOLDER_OPERATOR
literal placeholdermacroboostyapuser
https://www.boost.org/doc/libs/1_87_0/doc/html/doxygen/headers/user__macros_8hpp_1a41bd0e25eb1c4ebec282e3d444a15e66.html
Macro BOOST_YAP_USER_LITERAL_PLACEHOLDER_OPERATOR
literal placeholdermacroboostyapuser