# Convert a symmetric function into a polynomial on elementary symmetric functions

The following is a variant of a previous question (32569). What command fills in the blank?

```
sage: e = SymmetricFunctions(QQ).e()
sage: u = e[3](e[2])
sage: u
e[3, 3] + e[4, 1, 1] - 2*e[4, 2] - e[5, 1] + e[6]
sage: R.<e1,e2,e3,e4,e5,e6> = PolynomialRing(QQ, 6)
sage: p = _the_blank_() # What command goes here?
sage: p
e1^2*e4 + e3^2 - 2*e2*e4 - e1*e5 + e6
```