code: def encode_data_items(self, *args):
          
          str_list = []
          for arg in args:
  
              # encode string items as-is
              if isinstance(arg, str):
                  arg_str = arg
  
              # encode integer items as base-64 strings with a '~' character in front
              elif isinstance(arg, int):
                  arg_str = self.INTEGER_PREFIX + self.encode_int(arg)
  
              # convert other types to string
              else:
                  arg_str = str(arg)
  
              str_list.append(arg_str)
  
          # Concatenate strings with '|' separators
          concatenated_str = self.SEPARATOR.join(str_list)
  
          return concatenated_str
docs: Encodes a list of integers and strings into a concatenated string.
  
          - encode string items as-is.
          - encode integer items as base-64 with a ``'~'`` prefix.
          - concatenate encoded items with a ``'|'`` separator.
  
          Example:
              ``encode_data_items('abc', 123, 'xyz')`` returns ``'abc|~B7|xyz'``