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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def check_installation(cur_file):
 """Warn user if running cleverhans from a different directory than tutorial."""

  cur_dir = os.path.split(os.path.dirname(os.path.abspath(cur_file)))[0]
  ch_dir = os.path.split(cleverhans.__path__[0])[0]
  if cur_dir != ch_dir:
    warnings.warn("It appears that you have at least two versions of "
                  "cleverhans installed, one at %s and one at"
                  " %s. You are running the tutorial script from the "
                  "former but python imported the library module from the "
                  "latter. This may cause errors, for example if the tutorial"
                  " version is newer than the library version and attempts to"
                  " call new features." % (cur_dir, ch_dir))