reduce function

Did you try taking a look at the documentation and running the sample code in your environment to understand its functioning?

yes harshit  i have tried this

reduce(
  function: rule!SB_sum(number: _,sum:_),
 initial:0,
list:{1,2,3},
context:1
)

getting this error

Like the error says, you will need to remove the keywords.

Hey,

Take 3 parameters in the function named: rule!SB_sum

This is how it will work:

Hey,

Take 3 parameters in the function named: rule!SB_sum

This is how it will work: