SeqCst
In addition to the guarantees of AcqRel, there is a global total order
on all sequentially-consistent operations on all addresses, which is
consistent with the happens-before partial order and with the
modification orders of all the affected addresses.
trait Singleton
trait Product
trait Mirror
trait Serializable
trait Product
trait Equals
class MemoryOrder
class Object
trait Matchable
class Any
SeqCst.type