MoveAssignable
t, a modifiable lvalue expression （http://en.cppreference.com/w/cpp/language/value_category）of type T
rv, an rvalue （http://en.cppreference.com/w/cpp/language/value_category）expression of type T
CopyAssignable
t, a modifiable lvalue expression （http://en.cppreference.com/w/cpp/language/value_category）of type T
v, an lvalue （http://en.cppreference.com/w/cpp/language/value_category）expression of type T or const T or an rvalue （http://en.cppreference.com/w/cpp/language/value_category）expression of type const T
MoveConstructible
Specifies that an instance of the type can be constructed from an rvalue （http://en.cppreference.com/w/cpp/language/value_category）argument.
rv, an rvalue （http://en.cppreference.com/w/cpp/language/value_category）expression of type T
u, an arbitrary identifier
CopyConstructible
Specifies that an instance of the type can be copy-constructed from an lvalue expression.（http://en.cppreference.com/w/cpp/language/value_category）
T u = v;T(v)
