code: def test_is_pi_parallel(self):
      ring1_center = np.array([0.0, 0.0, 0.0])
      ring2_center_true = np.array([4.0, 0.0, 0.0])
      ring2_center_false = np.array([10.0, 0.0, 0.0])
      ring1_normal_true = np.array([1.0, 0.0, 0.0])
      ring1_normal_false = np.array([0.0, 1.0, 0.0])
  
      for ring2_normal in (
          np.array([2.0, 0, 0]),
          np.array([-3.0, 0, 0]),
      ):
          # parallel normals
          self.assertTrue(
              is_pi_parallel(
                  ring1_center,
                  ring1_normal_true,
                  ring2_center_true,
                  ring2_normal,
              )
          )
          # perpendicular normals
          self.assertFalse(
              is_pi_parallel(
                  ring1_center,
                  ring1_normal_false,
                  ring2_center_true,
                  ring2_normal,
              )
          )
          # too far away
          self.assertFalse(
              is_pi_parallel(
                  ring1_center,
                  ring1_normal_true,
                  ring2_center_false,
                  ring2_normal,
              )
          )
  
imports: import os
  import unittest
  import numpy
  from deepchem.utils.rdkit_utils import load_molecule
  from deepchem.utils.rdkit_utils import compute_ring_center
  from deepchem.utils.rdkit_utils import compute_ring_normal
  from deepchem.utils.noncovalent_utils import is_pi_parallel
  from deepchem.utils.noncovalent_utils import is_pi_t
  from deepchem.utils.noncovalent_utils import compute_pi_stack
  from deepchem.utils.noncovalent_utils import is_cation_pi
  from deepchem.utils.noncovalent_utils import compute_cation_pi
  from deepchem.utils.noncovalent_utils import compute_binding_pocket_cation_pi
label_desc: Use image node_id 4 for calling the TestPiInteractions obj's underlying member method code with example usage: obj.test_is_pi_parallel() without return types