import math


def angle_between_vectors(vector1, vector2):
    """ Returns the angle in radians between vectors 'vector1' and 'vector2'::
             angle_between((1, 0, 0), (0, 1, 0)): 1.5707963267948966
             angle_between((1, 0, 0), (1, 0, 0)): 0.0
             angle_between((1, 0, 0), (-1, 0, 0)): 3.141592653589793"""

    return math.atan2(vector2[0], vector2[2]) - math.atan2(vector1[0], vector1[2])