1 | initial version |

You should write:

```
sage: f = X^q + pi*X
sage: f
(2 + O(2^21))*X + (1 + O(2^20))*X^2
```

Otherwise, while writing `f(X)=...`

you redefine `X`

as being an element of the symbolic ring:

```
sage: f(X) = X^q + pi*X
TypeError: unsupported operand parent(s) for '*': 'Unramified Extension of 2-adic Field with capped relative precision 20 in omega defined by (1 + O(2^20))*x^2 + (1 + O(2^20))*x + (1 + O(2^20))' and 'Symbolic Ring'
sage: X.parent()
Symbolic Ring
```

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