I Keep getting this error, It's so simple and error is about (-x) in function but I don't know how I can fix it.
Please help me.

This is my code:

```
import numpy as np
x = list(np.arange(0, 1, 0.1))
print (x)
def f(x):
    f = np.exp(-x)
    return f

y =f(x)

print (y)

```