20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.17 Polymorphic function wrappers [func.wrap]

20.14.17.3 Class template function [func.wrap.func]

20.14.17.3.3 Modifiers [func.wrap.func.mod]

void swap(function& other) noexcept;
Effects: Interchanges the target objects of *this and other.