d = FunctionDefinition(real, 'rms', [arr, s], body, attrs=[bind_C('rms')])
    >>> print(fcode(fd, source_format='free', standard=2003))
    real*8 function rms(a, s) bind(C, name="rms")
    real*8, dimension(s), intent(in) :: a
    integer*4 :: s
    rms = sqrt(sum(a**2)/s)
    end function

    Ú