text: import pandas as pd
  import json
  
  from datetime import datetime
  
  
  _HELLOSKILL = './app/database/hello_skill.csv'
  _BYESKILL = './app/database/bye_skill.csv'
  _FALLSKILL = './app/database/fallback_skill.csv'
  
  
  def save_skill(data):
      data = data['data']
      pd.DataFrame(data['data']).replace(r'^\s*$', 'NULL', regex=True).to_csv('./app/database/' + data['name'] + '.csv',
                                                                              index=False,
                                                                              na_rep='NULL')
      return 'ok'
  
  
  def get_skill():
      hello = pd.read_csv(_HELLOSKILL)
      bye = pd.read_csv(_BYESKILL)
      fall = pd.read_csv(_FALLSKILL)
      data = {
          'hello': hello.where((pd.notnull(hello)), None).to_dict(),
          'bye': bye.where((pd.notnull(bye)), None).to_dict(),
          'fallback': fall.where((pd.notnull(fall)), None).to_dict(),
      }
      return json.dumps(data, ensure_ascii=False)
  
  
  def remove_skill(data):
      return 'ok'
  
  
  def add_skill(data):
      return 'ok'
  
  
  
  