Make this shared pointer manage the same modifiable object as the specified rhs shared pointer to the (template parameter) type COMPATIBLE_TYPE, use the same deleter as rhs, and refer to (ELEMENT_TYPE *)rhs.get(); return a reference providing modifiable access to this shared pointer. Note that if rhs is empty, then this shared pointer will also be empty after the assignment. Also note that if *this is the same object as rhs, then this method has no effect.