# Concurrently safe modifiers

All member functions in this section can be performed concurrently with each other.

reference local()

  If there is no current element corresponding to the current thread, this method constructs a new element. A new element is copy-constructed if an exemplar was provided to the constructor for `*this`; otherwise, a new element is default-constructed.

  Returns: A reference to the element of `*this` that corresponds to the current thread.

reference local(bool &exists)

  Similar to `local()`, except that `exists` is set to true if an element was already present for the current thread; false, otherwise.

  Returns: Reference to the thread-local element.