What you are looking for is probably the user-api-usage endpoint.
According to the linked api-docs, the JSON object returned is of the format:
{
"data": {
"daily": {
"2020-08-10": {
"urls": 2
},
"2020-08-11": {
"domains": 1,
"file_relationships": 1,
"files": 1
},
"2020-08-12": {
"analyses": 25,
"file_analyse": 3,
"files": 6
},
"2020-08-17": {
"urls": 3
},
"2020-08-18": {
"urls": 1
},
"2020-08-20": {
"file_download": 36,
"file_relationships": 5,
"files": 1
},
"2020-08-21": {
"file_analyse": 1,
"file_download": 92,
"files": 1
},
"2020-08-23": {
"analyses": 5,
"file_analyse": 1
},
"2020-08-25": {
"file_download": 51
},
"2020-08-26": {
"file_download": 51
},
"2020-08-28": {
"file_download": 14
},
"2020-08-31": {
"file_download": 6
},
"2020-09-01": {
"file_download": 81
},
"2020-09-02": {
"file_relationships": 5,
"graphs": 1
},
"2020-09-03": {
"file_relationships": 6,
"graph_comments": 1,
"graph_items": 3,
"graphs": 2,
"retrohunt_jobs": 2
},
{
...
}
},
"total": {
"analyses": 30,
"comment_relationships": 1,
"comments": 4,
"domain_comments": 1,
"domain_graphs": 2,
"domain_relationships": 2,
"domains": 1,
"file_analyse": 6,
"file_behaviours": 6,
"file_download": 331,
"file_relationships": 19,
"files": 9,
"graph_comments": 2,
"graph_items": 3,
"graphs": 8,
"intelligence_search": 5,
"resolutions": 1,
"retrohunt_jobs": 2,
"search": 6,
"statistics": 1,
"submissions": 1,
"url_relationships": 1,
"urls": 8
}
}
}
Which gives you both a by-date breakdown and a "totals" node at the bottom of the stream/file.
The command that the documentation recommends is as follows:
curl --request GET \
--url https://www.virustotal.com/api/v3/users/{id}/api_usage \
--header 'x-apikey: <your API key>'
Again, the source for this info is linked above.
EDIT:
A python function commonly used to run shell commands like curl is the system.os() function. There are other (and possibly even better) solutions for this, but that is out of scope for this answer. To use it in your script, you would add:
/usr/bin/env python
import system
...
system.os('curl --request GET --url https://www.virustotal.com/api/v3/users/{id}/api_usage --header \'x-apikey: <your API key>\'')
...to your script (Notice the added backslashes escaping the inner quotes.)