def exit_normal():
    """Returns loss coefficient for any exit to a pipe
    as shown in [1]_ and in other sources.

    .. math::
        K = 1

    .. figure:: fittings/flush_mounted_exit.png
       :scale: 28 %
       :alt: Exit from a flush mounted wall; after [1]_

    Returns
    -------
    K : float
        Loss coefficient [-]

    Notes
    -----
    It has been found on occasion that K = 2.0 for laminar flow, and ranges
    from about 1.04 to 1.10 for turbulent flow.

    Examples
    --------
    >>> exit_normal()
    1.0

    References
    ----------
    .. [1] Rennels, Donald C., and Hobart M. Hudson. Pipe Flow: A Practical
       and Comprehensive Guide. 1st edition. Hoboken, N.J: Wiley, 2012.
    """
    return 1.0
