TODO docs.

def nautical(kilometers=0, meters=0, miles=0, feet=0):
    """
    TODO docs.
    """
    ret = 0.
    if feet:
        kilometers += feet / ft(1.)
    if miles:
        kilometers += km(miles=miles)
    if meters:
        kilometers += meters / 1000.
    ret += kilometers / 1.852
    return ret