numpy array of lists to 1d array? (flatten array of list objects) [duplicate]

I have to flatten array of lists to 1d numpy array. I use this:

import numpy as np

orig = np.array([[1,2], [3]], dtype=object)

lst = []
for x in orig:
    lst.extend(x)

result = np.array(lst)  # makes array([1, 2, 3])

Is there a standard numpy function or method to do this (similar to np.flatten)?