You can embed functions as arguments within a function.
Example:
In the following example, the function Average is embedded in the function Sum:
sum(row[3:5], avg(row[4:6], 40, 50), row[7; 9], 70, 80)
Row segments 3, 4 and 5
The average of row segments 4, 5 and 6, with the numbers 40 and 50
Row segments 7 and 9
The numbers 70 and 80