-/** Return a reference to the pseries object embedded in an expression.
- * The result is undefined if the expression does not contain a pseries
- * object at its top level.
- *
- * @param e expression
- * @return reference to pseries object
- * @see is_a<> */
-inline const pseries &ex_to_pseries(const ex &e)
-{
- return static_cast<const pseries &>(*e.bp);
-}