Based on prior knowledge, gender can be a potential factor in the development of chronic heart failure. It is known that males have a higher incidence of heart disease compared to females. Therefore, it is reasonable to assume that the presence or absence of chronic heart failure may differ based on gender.

To analyze the relationship between the feature "SEX" and the target variable "chronic heart failure", we can examine the distribution of genders among patients with and without chronic heart failure.

We can create a dictionary with the possible values of the feature "SEX" for the target classes "no" and "yes":

```json
{
	"no": ["male", "female"],
	"yes": ["male", "female"]
}
```

This dictionary indicates that both genders, male and female, could be present in both the "no" and "yes" target classes.