def _maybe_coerce_values(self, values):
if isinstance(values, (ABCIndexClass, ABCSeries)):<EOL><INDENT>values = values._values<EOL><DEDENT>return values<EOL>
Unbox to an extension array.

        This will unbox an ExtensionArray stored in an Index or Series.
        ExtensionArrays pass through. No dtype coercion is done.

        Parameters
        ----------
        values : Index, Series, ExtensionArray

        Returns
        -------
        ExtensionArray