Reads one value out of a step's result, by the output mapping's key.
Three forms, in the order they are tried: * means the whole result; a dotted key walks into it;
anything else is a single field. Field lookup is case-insensitive at every level, because an
action's declared output names and the casing an author types rarely agree, and a case-sensitive
miss would silently map nothing.
Reads one value out of a step's result, by the output mapping's key.
Three forms, in the order they are tried:
*means the whole result; a dotted key walks into it; anything else is a single field. Field lookup is case-insensitive at every level, because an action's declared output names and the casing an author types rarely agree, and a case-sensitive miss would silently map nothing.