code: def check_time_only(time, signal, verb):
      r
      global _min_time
  
      # Check input signal
      if int(signal) not in [-1, 0, 1]:
          print("* ERROR   :: <signal> must be one of: [None, -1, 0, 1]; " +
                "<signal> provided: "+str(signal))
          raise ValueError('signal')
  
      # Check time
      time = _check_var(time, float, 1, 'time')
  
      # Minimum time to avoid division by zero  at time = 0 s.
      # => min_time can be set with utils.set_min
      time = _check_min(time, _min_time, 'Times', 's', verb)
      if verb > 2:
          _prnt_min_max_val(time, "   time        [s] : ", verb)
  
      return time
docs: r"""Check time and signal parameters.
  
      This check-function is called from one of the modelling routines in
      :mod:`model`.  Consult these modelling routines for a detailed description
      of the input parameters.
  
      Parameters
      ----------
      time : array_like
          Times t (s).
  
      signal : {None, 0, 1, -1}
          Source signal:
              - None: Frequency-domain response
              - -1 : Switch-off time-domain response
              - 0 : Impulse time-domain response
              - +1 : Switch-on time-domain response
  
      verb : {0, 1, 2, 3, 4}
          Level of verbosity.
  
  
      Returns
      -------
      time : float
          Time, checked for size and assured min_time.