Assign to this object the value of the specified rhs object, propagate to this object the allocator of rhs if the ALLOCATOR type has trait propagate_on_container_copy_assignment, and return a reference providing modifiable access to this object. If an exception is thrown, *this is left in a valid but unspecified state. This method requires that the (template parameter) type VALUE be copy-assignable and copy-insertable into this list. Note that, to the extent possible, existing elements of this list are copy-assigned to, to minimize the number of nodes that need to be copy-inserted or erased.