DataFrame.first_valid_index()

DataFrame.to_csv(path_or_buf=None, sep=', ', na_rep='', float_format=None, columns=None, header=True, index=True, index_label=None, mode='w'

Panel.reindex_axis(labels, axis=0, method=None, level=None, copy=True, limit=None, fill_value=nan)

Panel.median(axis=None, skipna=None, level=None, numeric_only=None, **kwargs)

Panel.groupby(function, axis='major')

Index.sort_values(return_indexer=False, ascending=True)

Index.inferred_type = None

Index.nbytes return the number of bytes in the underlying data

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

DatetimeIndex.sym_diff(*args, **kwargs)