# Pastebin 8AcLydOj
```python twitter_wallaroo_app.pyTraceback (most recent call last):
  File "twitter_wallaroo_app.py", line 20, in <module>
    @wallaroo.encoder
  File "/home/nisan/wallaroo-tutorial/wallaroo/machida/wallaroo.py", line 322, in encoder
    _validate_arity_compatability(encoder_function, 1)
  File "/home/nisan/wallaroo-tutorial/wallaroo/machida/wallaroo.py", line 218, in _validate_arity_compatability
    ).format(arity))
wallaroo.WallarooParameterError: Incompatible function arity, your function must allow 1 arguments.```