def unmap_address(library, session):
    """Unmaps memory space previously mapped by map_address().

    Corresponds to viUnmapAddress function of the VISA library.

    :param library: the visa library wrapped by ctypes.
    :param session: Unique logical identifier to a session.
    :return: return value of the library call.
    :rtype: :class:`pyvisa.constants.StatusCode`
    """
    return library.viUnmapAddress(session)
