# converting to sympy

Dear All

I would like to convert a sage equation to sympy, eg

```
x=var('x')
y=2*x+Ei(x)
y._sympy_()
```

... and get complains that Ei is not defined in sympy.

How can I define a (possibly fake) Ei function in sympy from sage? Or is there any other way to avoid the problem?

Thanks

Valery