code: def multipart_encoder(**kwargs):
      
      def get_filetype(file_path):
          file_type = filetype.guess(file_path)
          if file_type:
              return file_type.mime
          else:
              return "text/html"
  
      fields_dict = {}
      for key, value in kwargs.items():
  
          if os.path.isabs(value):
              _file_path = value
              is_file = True
          else:
              global PWD
              _file_path = os.path.join(PWD, value)
              is_file = os.path.isfile(_file_path)
  
          if is_file:
              filename = os.path.basename(_file_path)
              with open(_file_path, 'rb') as f:
                  mime_type = get_filetype(_file_path)
                  fields_dict[key] = (filename, f.read(), mime_type)
          else:
              fields_dict[key] = value
  
      return MultipartEncoder(fields=fields_dict)
docs: initialize MultipartEncoder with uploading fields.