text: #!/usr/bin/python
  import sys
  import io
  import os
  import logging
  import numpy as np
  testdir = os.path.dirname(__file__)
  srcdir = '../parsevasp'
  sys.path.insert(0, os.path.abspath(os.path.join(testdir, srcdir)))
  import poscar
  
  logging.basicConfig(level=logging.DEBUG)
  logger = logging.getLogger('Testing')
  
  poscar = poscar.Poscar(file_path = testdir + "/POSCAREXT")
  
  poscar.modify("unitcell", np.array([[2.0, 0.0, 0.0],
                                   [0.0, 2.0, 0.0],
                                   [0.0, 0.0, 2.0]]))
  poscar.delete_site(2)
  
  poscar.write(file_path = testdir + "/POSCAREXTMOD")
  