What's the function of the ouput_1

[w5688414]

I found every node will return a string output_1，I can't figure out the purpose

haystack/haystack/nodes/ranker/base.py

Line 47 in dcb132b

return output, "output_1"

[anakin87]

This is the core concept:

A regular node usually has one outgoing edge and one return value. If you're creating a decision node, it typically has more than one outgoing edge. The run() and run_batch() methods of a decision node consist of a decision function that determines the path in the graph for sending the node's input. Such a function has more than one possible return value and each return value is named accordingly, for example: output_1 and output_2.

The following image can be useful for understanding this concept:

You can learn more about this topic in the docs: Nodes overview and Custom nodes.