Shift the bits of an integer to the left.
Bits are shifted to the left by appending x2 0s at the right of x1. Since the internal representation of numbers is in binary format, this operation is equivalent to multiplying x1 by 2**x2.
x1 : array_like of integer type
x2 : array_like of integer type
out : array of integer type
>>> np.left_shift(5, [1,2,3]) array([10, 20, 40])