wcs.skl.compose.get_feature_names() failes if ColumnTransformer has 1D column vector(s)

[snowdd1]

If columns from a pd.DataFrame are listed as String and not as List of Strings, get_feature_names fails with

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-104-fd28a853c8d9> in <module>()
----> 1 get_feature_names(p[0].transformers[0][1])

/usr/local/lib/python3.6/dist-packages/wcs/skl/compose.py in get_feature_names(sklearn_object, input_features)
    107     else:
    108         # pass on
--> 109         return sklearn_object.get_feature_names(input_features)
    110 
    111 

TypeError: get_feature_names() takes 1 positional argument but 2 were given