"time is not initialized. Have you called init_node()?" error: ROS & Baxter_interface

edit

I get this error whenever i run my code. the code itself is supposed to move my robot's arm in the given position. can anyone tell me what's wrong? why do i get this error when ive already called the rospy.init?

#!/usr/bin/env python
import rospy
import baxter_interface
from baxter_interface import Limb
import sys
import rospy
import numpy as np
import roslib

class arm_to_pos:

  def __init__(self):
    self.left_arm = Limb('left')

  def move_arm(self):
    self.left_arm.move_to_joint_positions(dict({'s0':0.0,'s1':-0.55,'e0':0.0,
        'e1':0.75,'w0':0.0,'w1':1.26,'w2':0.0}), timeout = 15.0)

def main():
  position = arm_to_pos()
  rospy.init_node('arm_to_pos', anonymous=True)
  position.move_arm()
  rospy.spin()

if __name__ == '__main__':
    main()