如何输出python中list的维度

import numpy as np
a = [[1,2],[3,4]]
print(np.array(a).shape)

>>> import numpy as np
>>> a=np.arange(12)
>>> a
array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
>>> a.reshape(2,6) 
array([[ 0, 1, 2, 3, 4, 5],
 [ 6, 7, 8, 9, 10, 11]])
>>> a
array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
>>> a.reshape(2,3,2) 
array([[[ 0, 1], 
 [ 2, 3],
 [ 4, 5]],

 [[ 6, 7],
 [ 8, 9],
 [10, 11]]])
>>> a.resize(2,6)
>>> a
>>> array([[ 0, 1, 2, 3, 4, 5],
 [ 6, 7, 8, 9, 10, 11]])
>>> a.shape=(2,6)
>>> a
array([[ 0, 1, 2, 3, 4, 5],
 [ 6, 7, 8, 9, 10, 11]])
>>> a.shape=(2,3,2)
>>> a
array([[[ 0, 1],
 [ 2, 3],
 [ 4, 5]],

 [[ 6, 7],
 [ 8, 9],
 [10, 11]]])
>>>