code: def find_first_existing_executable(exe_list):
      
      for filepath, opts in exe_list:
          try:
              proc = subprocess.Popen([filepath, opts],
                                      stdout=subprocess.PIPE,
                                      stderr=subprocess.PIPE)
              proc.communicate()
          except OSError:
              pass
          else:
              return filepath
docs: Accepts list of [('executable_file_path', 'options')],
      Returns first working executable_file_path