function angle$1(a, b) {
    var ax = a[0],
        ay = a[1],
        az = a[2],
        bx = b[0],
        by = b[1],
        bz = b[2],
        mag = Math.sqrt((ax * ax + ay * ay + az * az) * (bx * bx + by * by + bz * bz)),
        cosine = mag && dot$4(a, b) / mag;
    return Math.acos(Math.min(Math.max(cosine, -1), 1));
  }
Get the angle between two 3D vectors
@param {ReadonlyVec3} a The first operand
@param {ReadonlyVec3} b The second operand
@returns {Number} The angle in radians