Append to the end of this vector the specified move-insertable value. value is left in a valid but unspecified state. If an exception is thrown (other than by the move constructor of a non-copy-insertable value_type), *this is unaffected. Throw std::length_error if size() == max_size(). This method requires that the (template parameter) type VALUE_TYPE be move-insertable into this vector (see {Requirements on VALUE_TYPE}).