y.tail 
    * [ pandas.core.groupby.DataFrameGroupBy.take ](pandas.core.groupby.DataFrameGroupBy.take.html)
    * [ pandas.core.groupby.DataFrameGroupBy.value_counts ](pandas.core.groupby.DataFrameGroupBy.value_counts.html)
    * [ pandas.core.groupby.SeriesGroupBy.all ](pandas.core.groupby.SeriesGroupBy.all.html)
    * [ pandas.core.groupby.SeriesGroupBy.any ](pandas.core.groupby.SeriesGroupBy.any.html)
    * [ pandas.core.groupby.SeriesGroupBy.bfill ](pandas.core.groupby.SeriesGroupBy.bfill.html)
    * [ pandas.core.groupby.SeriesGroupBy.corr ](pandas.core.groupby.SeriesGroupBy.corr.html)
    * [ pandas.core.groupby.SeriesGroupBy.count ](pandas.core.groupby.SeriesGroupBy.count.html)
    * [ pandas.core.groupby.SeriesGroupBy.cov ](pandas.core.groupby.SeriesGroupBy.cov.html)
    * [ pandas.core.groupby.SeriesGroupBy.cumcount ](pandas.core.groupby.SeriesGroupBy.cumcount.html)
    * [ pandas.core.groupby.SeriesGroupBy.cummax ](pandas.core.groupby.SeriesGroupBy.cummax.html)
    * [ pandas.core.groupby.SeriesGroupBy.cummin ](pandas.core.groupby.SeriesGroupBy.cummin.html)
    * [ pandas.core.groupby.SeriesGroupBy.cumprod ](pandas.core.groupby.SeriesGroupBy.cumprod.html)
    * [ pandas.core.groupby.SeriesGroupBy.cumsum ](pandas.core.groupby.SeriesGroupBy.cumsum.html)
    * [ pandas.core.groupby.SeriesGroupBy.describe ](pandas.core.groupby.SeriesGroupBy.describe.html)
    * [ pandas.core.groupby.SeriesGroupBy.diff ](pandas.core.groupby.SeriesGroupBy.diff.html)
    * [ pandas.core.groupby.SeriesGroupBy.ffill ](pandas.core.groupby.SeriesGroupBy.ffill.html)
    * [ pandas.core.groupby.SeriesGroupBy.fillna ](pandas.core.groupby.SeriesGroupBy.fillna.html)
    * [ pandas.core.groupby.SeriesGroupBy.first ](pandas.core.groupby.SeriesGroupBy.first.html)
    * [ pandas.core.groupby.SeriesGroupBy.head ](pandas.core.groupby.SeriesGroupBy.head.html)
    * [ pandas.core.groupby.SeriesGroupBy.last ](pandas.core.groupby.SeriesGroupBy.last.html)
    * [ pandas.core.groupby.SeriesGroupBy.idxmax ](pandas.core.groupby.SeriesGroupBy.idxmax.html)
    * [ pandas.core.groupby.SeriesGroupBy.idxmin ](pandas.core.groupby.SeriesGroupBy.idxmin.html)
    * [ pandas.core.groupby.SeriesGroupBy.is_monotonic_increasing ](pandas.core.groupby.SeriesGroupBy.is_monotonic_increasing.html)
    * [ pandas.core.groupby.SeriesGroupBy.is_monotonic_decreasing ](pandas.core.groupby.SeriesGroupBy.is_monotonic_decreasing.html)
    * [ pandas.core.groupby.SeriesGroupBy.max ](pandas.core.groupby.SeriesGroupBy.max.html)
    * [ pandas.core.groupby.SeriesGroupBy.mean ](pandas.core.groupby.SeriesGroupBy.mean.html)
    * [ pandas.core.groupby.SeriesGroupBy.median ](pandas.core.groupby.SeriesGroupBy.median.html)
    * [ pandas.core.groupby.SeriesGroupBy.min ](pandas.core.groupby.SeriesGroupBy.min.html)
    * [ pandas.core.groupby.SeriesGroupBy.ngroup ](pandas.core.groupby.SeriesGroupBy.ngroup.html)
    * [ pandas.core.groupby.SeriesGroupBy.nlargest ](pandas.core.groupby.SeriesGroupBy.nlargest.html)
    * [ pandas.core.groupby.SeriesGroupBy.nsmallest ](pandas.core.groupby.SeriesGroupBy.nsmallest.html)
    * [ pandas.core.groupby.SeriesGroupBy.nth ](pandas.core.groupby.SeriesGroupBy.nth.html)
    * [ pandas.core.groupby.SeriesGroupBy.nunique ](pandas.core.groupby.SeriesGroupBy.nunique.html)
    * [ pandas.core.groupby.SeriesGroupBy.unique ](pandas.core.groupby.SeriesGroupBy.unique.html)
    * [ pandas.core.groupby.SeriesGroupBy.ohlc ](pandas.core.groupby.SeriesGroupBy.ohlc.html)
    * [ pandas.core.groupby.SeriesGroupBy.pct_change ](pandas.core.groupby.SeriesGroupBy.pct_change.html)
    * [ pandas.core.groupby.SeriesGroupBy.prod ](pandas.core.groupby.SeriesGroupBy.prod.html)
    * [ pandas.core.groupby.SeriesGroupBy.quantile ](pandas.core.groupby.SeriesGroupBy.quantile.html)
    * [ pandas.core.groupby.SeriesGroupBy.rank ](pandas.core.groupby.SeriesGroupBy.rank.html)
    * [ pandas.core.groupby.SeriesGroupBy.resample ](pandas.core.groupby.SeriesGroupBy.resample.html)
    * [ pandas.core.gr