This special concept enables various useful default behavior that makes any act like an ordinary object. By default any forwards all operations to the underlying type, and provides only the operations that are specified in its
In detail, relaxed enables the following:
A raw value can be assigned to an any. This will replace the value stored by the any. (But note that if assignable is present, it takes priority.)
default construction of any is allowed and creates a null any.
equality_comparable: If the types do not match, it will return false.
less_than_comparable: If the types do not match, the ordering will be according to
if the arguments to any other function do not match, it will throw a bad_function_call exception instead of having undefined behavior.