code: def check_if_parallel(dx1, dy1, dx2, dy2, tolerence=1.0e-5):
      """returns
      * 1 if two lines are parralel in same direction
      * -1 if two lines are parralel in opposite direction
      * 0 otherwise
      """
      theta1 = np.arctan2(dx1, dy1)
      theta2 = np.arctan2(dx2, dy2)
      dtheta = np.abs(theta1 - theta2)
      if dtheta < tolerence:
          return 1
      elif np.abs(dtheta - np.pi) < tolerence:
          return -1
      else:
          return False
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import numpy
  from matplotlib.path import Path
  from operator import xor
  import warnings
label_desc: Use image node_id 11 for calling a global function with example usage: check_if_parallel(dx1, dy1, dx2, dy2, tolerence) and returns: int, unknown, False