Help - count values of a certain attribute

Configuration
1

Hi just a quick question, wanted to created a seperate topic for this.
Is it possible to count the values of a certain sensor attribute?

so for instance I’ve got a rest sensor which gives me an output like

rows:
  - keys:
      - key1
    clicks: 0
    impressions: 4
    ctr: 0
    position: 85
  - keys:
      - key2
    clicks: 0
    impressions: 5
    ctr: 0
    position: 59
  - keys:
      - key3
    clicks: 0
    impressions: 1
    ctr: 0
    position: 59

I want to count the impressions, so in this example I expect the result 10.
But when I try to execute the following template in the template tester:

{{ state_attr('sensor.google_api', 'rows') 
|  selectattr('impressions') | list | count }}

it counts not the impressions but the amount of “keys” values. so in this example 3 ?!
I cant find such solution on the forum yet.

2 
{{ state_attr('sensor.google_api', 'rows') | map(attribute='impressions') | sum }}