text: 
  import pandas as pd
  from pandas import DataFrame as df
  import numpy as np
  import os
  
  inputfile_dir='./inputfile'
  outputfile='all2.csv'
  for inputfile in os.listdir(inputfile_dir):
      inputfile1=os.path.join("./inputfile",inputfile)
      df = pd.read_csv(inputfile1)
      df.to_csv(outputfile,index=False, header=False, mode='a+')
  