Why `small = -1000` ?

[gaoisbest]

In file model.py line 288, small = -1000 is used to construct

b_s = np.array([[small] * n_tags + [0, small]]).astype(np.float32)
e_s = np.array([[small] * n_tags + [small, 0]]).astype(np.float32)

I have two questions:
[1] Why does small equal to -1000 ?
[2] Why b_s and e_s are construct like this ? What's the difference between [[small, small, ..., 0, small]] and [[small, small, ..., small, 0]]

Thanks.

[gaoisbest]

Have understand the principles.