tf transformPoint() equivalent on tf2?

edit

This is very tricky. I had to do

 import tf2_geometry_msgs.tf2_geometry_msgs

in order for the do_transform interfaces for PoseStamped and other geometry_msgs messages to be registered. The registration is done while importing as shown in the source code for tf2_geometry_msgs.py.

The comments by @Procópio and @Alkrick can be resolved by this.

This does not appear (from an end-user's perspective) to be relevant for the transform function. Either documentation should say this or the way to use tf2_ros should be improved (why not import the above automatically when doing import tf2_ros?)

Here's a sample script to do it, following @zkytony 's answer:

#!/usr/bin/env python3
import rospy
from geometry_msgs.msg import PoseStamped, TransformStamped
import tf2_ros
import tf2_geometry_msgs.tf2_geometry_msgs

one = PoseStamped()

trans = TransformStamped()
trans.transform.translation.x = 1

print(one)

two = tf2_geometry_msgs.do_transform_pose(one, trans)
print(two)

The output will be:

header:
  seq: 0
  stamp: 
    secs: 0
    nsecs:         0
  frame_id: ''
pose:
  position: 
    x: 0.0
    y: 0.0
    z: 0.0
  orientation: 
    x: 0.0
    y: 0.0
    z: 0.0
    w: 0.0  

header:
  seq: 0
  stamp: 
    secs: 0
    nsecs:         0
  frame_id: ''
pose:
  position: 
    x: 1.0
    y: 0.0
    z: 0.0
  orientation: 
    x: 0.0
    y: 0.0
    z: 0.5
    w: 0.0