Can sum only calculate the value of count

Documentation
1

I want to query and calculate the cumulative sum of a certain predicate，for example, I want to obtain the age and。

{
result(func: type(Person)){
age
}

}

2

@lock Check out this part of docs: Aggregation - Query language
And section Sum and Avg

3

I have tried sum, but this can only calculate the value of count()
eg:

{
result(func: type(Person)){
v as count(age)
}
me(){
sum(val(v))
}

}

4

You can sum without using count():

{
  var(func: type(Person)){
    v as age
  }
  
  x(){
    sum(val(v))
  }
}
5

Thank you very much. I found that the field type I used earlier was incorrect