curve = bpy.data.curves[0].splines[0]
curve.bezier_points[0].co
curve.bezier_points[0].handle_left
curve.bezier_points[0].handle_right

spline = bpy.data.curves[0].splines[0]

if len(spline.bezier_points) >= 2:
    r = spline.resolution_u + 1
    segments = len(spline.bezier_points)
    if not spline.use_cyclic_u:
        segments -= 1

    points = []
    for i in range(segments):
        inext = (i + 1) % len(spline.bezier_points)

        knot1 = spline.bezier_points[i].co
        handle1 = spline.bezier_points[i].handle_right
        handle2 = spline.bezier_points[inext].handle_left
        knot2 = spline.bezier_points[inext].co

        _points = mathutils.geometry.interpolate_bezier(knot1, handle1, handle2, knot2, r)
        points.extend(_points)