Describe the maintenance task

pyaptamer/trafos/base/_base.py has three issues that should be addressed together:

1. Abstract methods raise ValueError instead of NotImplementedError

_fit, _transform, and _transform_element are abstract methods that raise
ValueError when called directly. Python's convention — and the convention used
by skbase.BaseEstimator which BaseTransform inherits from — is to raise
NotImplementedError for unimplemented abstract methods.

# Current (wrong):
def _fit(self, X, y=None):
    raise ValueError("abstract method _fit called, this should be implemented in the subclass")

# Should be:
def _fit(self, X, y=None):
    raise NotImplementedError("abstract method _fit called, this should be implemented in the subclass")

Using ValueError is misleading because it suggests the error is caused by bad
input values rather than a missing implementation. It can also cause issues if any
upstream code has a bare except ValueError clause that would silently swallow it.

The same applies to _transform and _transform_element.

2. Missing __author__ tag

Every other module in pyaptamer has __author__ = [...]. This file has none.

3. Missing __all__ tag

Every other public module in pyaptamer has __all__ = [...]. This file has none.

Files affected

• pyaptamer/trafos/base/_base.py

Fix

• Replace 3x raise ValueError(...) → raise NotImplementedError(...) for the abstract methods
• Add __author__ = ["nennomp", "fkiraly"] (consistent with _tags["authors"] in GreedyEncoder)
• Add __all__ = ["BaseTransform"]