code: def check_isolation_executable_installed(isolation_executable):
      '''
      Check that proot is installed.
      '''
      cmd = [isolation_executable, '--version']
      try:
          proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
          proc.communicate()
          return bool(proc.returncode == 0)
      except (OSError, ValueError) as e:
          if isinstance(e, ValueError) or getattr(e, 'errno', 1) != 2:  # ENOENT, no such file or directory
              raise RuntimeError('bwrap unavailable for unexpected reason.')
          return Falsf check_isolation_executable_installed(isolation_executable):
      '''
      Check that proot is installed.
      '''
      cmd = [isolation_executable, '--version']
      try:
          proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE)
          proc.communicate()
          return bool(proc.returncode == 0)
      except (OSError, ValueError) as e:
          if isinstance(e, ValueError) or getattr(e, 'errno', 1) != 2:  # ENOENT, no such file or directory
              raise RuntimeError('bwrap unavailable for unexpected reason.')
          return False
docs: Check that proot is installed.