How to use the pymap3d.utils.sign function in pymap3d

cos2sigmam
            + B
            / 4
            * (
                cos(sigma) * (-1 + 2 * cos2sigmam ** 2)
                - B / 6 * cos2sigmam * (-3 + 4 * sin(sigma) ** 2) * (-3 + 4 * cos2sigmam ** 2)
            )
        )
    )

    dist_m = b * A * (sigma - deltasigma)

    # %% From point #1 to point #2
    # correct sign of lambda for azimuth calcs:
    lamb = abs(lamb)
    if sign(sin(lon2 - lon1)) * sign(sin(lamb)) < 0:
        lamb = -lamb
    numer = cos(U2) * sin(lamb)
    denom = cos(U1) * sin(U2) - sin(U1) * cos(U2) * cos(lamb)
    a12 = atan2(numer, denom)
    a12 %= 2 * pi

    az = degrees(a12)

    return dist_m, az

ell = Ellipsoid()
    # %% Input check:
    if (abs(Lat1) > 90) | (abs(Lat2) > 90):
        raise ValueError("Input latitudes must be in [-90, 90] degrees.")
    # %% Supply WGS84 earth ellipsoid axis lengths in meters:
    a = ell.semimajor_axis
    b = ell.semiminor_axis
    f = ell.flattening
    # %% convert inputs in degrees to radians:
    lat1 = radians(Lat1)
    lon1 = radians(Lon1)
    lat2 = radians(Lat2)
    lon2 = radians(Lon2)
    # %% correct for errors at exact poles by adjusting 0.6 millimeters:
    if abs(pi / 2 - abs(lat1)) < 1e-10:
        lat1 = sign(lat1) * (pi / 2 - 1e-10)

    if abs(pi / 2 - abs(lat2)) < 1e-10:
        lat2 = sign(lat2) * (pi / 2 - 1e-10)

    U1 = atan((1 - f) * tan(lat1))
    U2 = atan((1 - f) * tan(lat2))
    lon1 = lon1 % (2 * pi)
    lon2 = lon2 % (2 * pi)
    L = abs(lon2 - lon1)
    if L > pi:
        L = 2 * pi - L

    lamb = copy(L)  # NOTE: program will fail without copy!
    itercount = 0
    warninggiven = False
    notdone = True

if ell is not None:
        a = ell.semimajor_axis
        b = ell.semiminor_axis
        f = ell.flattening
    else:  # Supply WGS84 earth ellipsoid axis lengths in meters:
        a = 6378137  # semimajor axis
        b = 6356752.31424518  # WGS84 earth flattening coefficient definition
        f = (a - b) / a

    lat1 = radians(Lat1)  # intial latitude in radians
    lon1 = radians(Lon1)  # intial longitude in radians

    # correct for errors at exact poles by adjusting 0.6 millimeters:
    if abs(pi / 2 - abs(lat1)) < 1e-10:
        lat1 = sign(lat1) * (pi / 2 - (1e-10))

    alpha1 = radians(Azim)  # inital azimuth in radians
    sinAlpha1 = sin(alpha1)
    cosAlpha1 = cos(alpha1)

    tanU1 = (1 - f) * tan(lat1)
    cosU1 = 1 / sqrt(1 + tanU1 ** 2)
    sinU1 = tanU1 * cosU1
    sigma1 = atan2(tanU1, cosAlpha1)
    sinAlpha = cosU1 * sinAlpha1
    cosSqAlpha = 1 - sinAlpha * sinAlpha
    uSq = cosSqAlpha * (a ** 2 - b ** 2) / b ** 2
    A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)))
    B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)))

    sigma = Rng / (b * A)

raise ValueError("Input latitudes must be in [-90, 90] degrees.")
    # %% Supply WGS84 earth ellipsoid axis lengths in meters:
    a = ell.semimajor_axis
    b = ell.semiminor_axis
    f = ell.flattening
    # %% convert inputs in degrees to radians:
    lat1 = radians(Lat1)
    lon1 = radians(Lon1)
    lat2 = radians(Lat2)
    lon2 = radians(Lon2)
    # %% correct for errors at exact poles by adjusting 0.6 millimeters:
    if abs(pi / 2 - abs(lat1)) < 1e-10:
        lat1 = sign(lat1) * (pi / 2 - 1e-10)

    if abs(pi / 2 - abs(lat2)) < 1e-10:
        lat2 = sign(lat2) * (pi / 2 - 1e-10)

    U1 = atan((1 - f) * tan(lat1))
    U2 = atan((1 - f) * tan(lat2))
    lon1 = lon1 % (2 * pi)
    lon2 = lon2 % (2 * pi)
    L = abs(lon2 - lon1)
    if L > pi:
        L = 2 * pi - L

    lamb = copy(L)  # NOTE: program will fail without copy!
    itercount = 0
    warninggiven = False
    notdone = True
    while notdone:  # force at least one execution
        itercount += 1
        if itercount > 50: