@Substitution(name='<STR_LIT>')<EOL><INDENT>@Appender(_common_see_also)<EOL>def all(self, skipna=True):<DEDENT>
return self._bool_agg('<STR_LIT:all>', skipna)<EOL>
Return True if all values in the group are truthful, else False.

Parameters
----------
skipna : bool, default True
    Flag to ignore nan values during truth testing