from tensor to list code example

Example 1: how can I covert a list of tensor into tensor?

l = list(torch.tensor([1,2,3]))
print(l)
>>>[tensor(1), tensor(2), tensor(3)]
k = torch.stack(l)
print(k)
>>>tensor([1, 2, 3])

Example 2: list to tensor

a = [1, 2, 3]
b = torch.FloatTensor(a)