Index.nunique(dropna=True)

Index.data return the data pointer of the underlying data

Series.str.lstrip(to_strip=None)

pandas.to_numeric(arg, errors='raise', downcast=None)

Series.order(na_last=None, ascending=True, kind='quicksort', na_position='last', inplace=False)

Series.dt.strftime(*args, **kwargs)

Series.cov(other, min_periods=None)

DataFrame.truediv(other, axis='columns', level=None, fill_value=None)

Panel.pow(other, axis=0)

class pandas.Series(data=None, index=None, dtype=None, name=None, copy=False, fastpath=False)