How to implement append in tensor

Law 1 ： Use list append, Again concat

import torch
T1 = torch.tensor([1,2,5,4]).unsqueeze_(0)
T2 = torch.tensor([1,2,3,4]).unsqueeze_(0)
T3 = torch.tensor([2,2,3,4]).unsqueeze_(0)
a = []
a.append(T1)
a.append(T2)
a.append(T3)

c = torch.cat(a,dim=0)

Law two ： Use it directly concat

for i in range(12):
    b = torch.randn(3)
    b.unsqueeze_(0)
    if i == 0:
        a = b
    else:
        a = torch.cat((a, b), dim=0)