DataFrameGroupBy.fillna(value=None, method=None, axis=None, inplace=False, limit=None, downcast=None, **kwargs)

CategoricalIndex.base return the base object if the memory of the underlying data is shared

CategoricalIndex.is_object()

CategoricalIndex.append(other)

StataReader.variable_labels()

Index.argsort(*args, **kwargs)

DataFrameGroupBy.resample(rule, *args, **kwargs)

DataFrame.isnull()

Series.head(n=5)

CategoricalIndex.hasnans = None