Here (in section "Actions"):

For instance, the Fibonacci action definition contains the following:

int32 order
---
int32[] sequence
---
int32[] sequence

I think the feedback_fieldname sequence is a typo, and should be partial_sequence.

Because it's what it's called here and here

Within the action directory, create a file called Fibonacci.action with the following contents:

int32 order
---
int32[] sequence
---
int32[] partial_sequence