docs: def booted(context=None):
      '''
      Return True if the system was booted with systemd, False otherwise.  If the
      loader context dict ``__context__`` is passed, this function will set the
      ``salt.utils.systemd.booted`` key to represent if systemd is running and
      keep the logic below from needing to be run again during the same salt run.
      '''
      contextkey = 'salt.utils.systemd.booted'
      if isinstance(context, dict):
          # Can't put this if block on the same line as the above if block,
          # because it willl break the elif below.
          if contextkey in context:
              return context[contextkey]
      elif context is not None:
          raise SaltInvocationError('context must be a dictionary if passed')
  
      try:
          # This check does the same as sd_booted() from libsystemd-daemon:
          # http://www.freedesktop.org/software/systemd/man/sd_booted.html
          ret = bool(os.stat('/run/systemd/system'))
      except OSError:
          ret = False
  
      try:
          context[contextkey] = ret
      except TypeError:
          pass
  
      return ret