Hey there ! I’m beginning to learn to code, and I just want a stimulus to be presented on a screen at a certain degree of visual angle. Here is my code for the moment:

```
import numpy as np
import time
#Functions
def make_dot(number_dots):
r = [];
for i in range (number_dots):
random_placex = np.random.normal()
random_placey = np.random.normal()
r.append(vis.Circle (win,radius = 0.08,units='deg',fillColor='white',pos=[random_placex,random_placey]))
return r
##how many dots?
nb_dots = 50
#Make a window
win = vis.Window(size=(500,600))
dots = make_dot(nb_dots)
for i in range(len(dots)):
dots[i].draw()
win.flip()
time.sleep(5)
```

And I get the following error message:

raise ValueError(msg % monitor.name)

I guess I need to define the monitor I’m working on; But I have currently absolutely no idea how to do this, and I’m just desparate to find a solution. Could someone help me please?