why is my syntax error expected an indented block

Question

class LinearModel():
  
 def __init__(self, features, target):
 self.X = features
 self.y = target
  
 def GradDesc(self, parameters, learningRate, cost):
 self.a = learningRate
 self.c = cost
 self.p = parameters
 return self.a, self.Cost(self.c), self.p
  
 def Cost(self,c):
 if c =='RMSE':
 return self.y
 elif c == 'MSE':
 return self.X
  
X=1
y=0
a = LinearModel(5,4)
print(a.GradDesc(2,0.01,'MSE'))
print(a.Cost('RMSE'))