Suppose the parabola $(y - k)^2 = 4(x - h)$, with vertex $A$, passes through $O = (0, 0)$ and $L = (0, 2)$. Let $D$ be an end point of the latus rectum. Let the $y$-axis intersect the axis of the parabola at $P$. Then $\angle PDA$ is equal to