it`.

    .. versionadded:: 0.24

feature_names_in_ : ndarray of shape (`n_features_in_`,)
    Names of features seen during :term:`fit`. Defined only when `X` has feature
    names that are all strings.

    .. versionadded:: 1.0

See Also
--------
MaxAbsScaler : Scale each feature by its maximum absolute value.
StandardScaler : Standardize features by removing the mean and
    scaling to unit variance.
LabelBinarizer : Binarize labels in a one-vs-all fashion.
MultiLabelBinarizer : Transform between iterable of iterables
    and a multilabel format.

Notes
-----
If `func` returns an output with a `columns` attribute, then the columns is enforced
to be consistent with the output of `get_feature_names_out`.

Examples
--------
>>> import numpy as np
>>> from sklearn.preprocessing import FunctionTransformer
>>> transformer = FunctionTransformer(np.log1p)
>>> X = np.array([[0, 1], [2, 3]])
>>> transformer.transform(X)
array([[0.       , 0.6931...],
       [1.0986..., 1.3862...]])
N