code: def miles(kilometers=0, meters=0, feet=0, nautical=0):
      
      ret = 0.
      if nautical:
          kilometers += nautical / nm(1.)
      if feet:
          kilometers += feet / ft(1.)
      if meters:
          kilometers += meters / 1000.
      ret += kilometers / 1.609344
      return ret
docs: TODO docs.