### Piecewise Symbolic Function with Conditional Statement

I wish to incorporate a conditional Python expression (`if ... else ...`

) in a symbolic function.

Suppose I have a piecewise function *k(n)* defined for *n* = 1,2,3... as in the following pseudocode:

```
k(n) =
2 if n = 1
n otherwise
```

I compose this with another function *g(x)* and wish to integrate the result. For example,

```
f(x)=g(x)/k(n)
f(n=...).integrate(x, 0, 1)
```

How can implement a non-evaluating conditional in a symbolic Sage function?