Accepts a string and returns a list of strings of numeric LSB runlevels.

def GetRunlevelsLSB(states):
  """Accepts a string and returns a list of strings of numeric LSB runlevels."""
  if not states:
    return set()
  valid = set(["0", "1", "2", "3", "4", "5", "6"])
  _LogInvalidRunLevels(states, valid)
  return valid.intersection(set(states.split()))