def METHOD_NAME(posture, positions, point=0):
    """Set the posture positions using a dict of joint positions."""
    # XXX: Why have we been doing this?
    # posture.header.stamp = now
    posture.joint_names = positions.keys()
    # Extend the array to be big enough.
    if len(posture.points) < point + 1:
        for _ in range(point + 1):
            posture.points.append(JointTrajectoryPoint())
    # Update the point in place
    jtp = JointTrajectoryPoint()
    for _, pos in positions.items():
        jtp.positions.append(pos)
    posture.points[point] = jtp