In a helper, you might consider to have a single exit point for clarity purpose.
This structure produces overly complex code easily replaced by range.
In Go 1.11, the code is on average 5% faster except towards the end of the searched range.
With Go 1.12, codes are equivalent as range is regularly catching up the while structure.
src>go test -bench=. ./singleexit
go version go1.11.1 windows/amd64
go version go1.12 windows/amd64
In the box, before the not found case, you can see the cost of exiting a for loop just before its end.
