code: def clampValues(self,timePoint=0):
          
          Cs=np.zeros(self.sweeps)
          for i in range(self.sweeps):
              self.setSweep(i) #TODO: protocol only = True
              for j in range(len(self.protoSeqX)):
                  if self.protoSeqX[j]<=timePoint*self.rate:
                      Cs[i]=self.protoSeqY[j]
          return Cs
docs: return an array of command values at a time point (in sec).
          Useful for things like generating I/V curves.