Python类返回TypeError:“list”对象不可调用

I have a class:

我有一个类:

class mountain:
  def __init__(self,pk_positions,chann_1,chann_2): 
    self.pk_positions = pk_positions
    self.chann_1 = chann_1
    self.chann_2 = chann_2
  def chann_1_pk(self):
    return(list(self.chann_1[i] for i in self.pk_positions))
  def chann_2_pk(self):
    return(list(self.chann_2[i] for i in self.pk_positions))
  def vall_positions(self):
    return(list(int((i+j)/2) for i,j in zip(self.pk_positions[:-1],self.pk_positions[1:])))
  def vall_sum(self):
    return(list(self.chann_1[i]+self.chann_2[i] for i in self.vall_positions()))
class mountain:
  d