code: def run(self):
  
          
          with open(self.output_file, "w") as f_std, \
                  open(self.stderr_file, "w", buffering=1) as f_err:
              # Use line buffering for stderr
              # On TSCC, need to run shell command
              p = subprocess.Popen(self.feff_cmd, stdout=f_std, stderr=f_err, shell=True)
  
          return p
docs: Performs the actual FEFF run
          Returns:
              (subprocess.Popen) Used for monitoring.