One of the most deciding skills that we look for in a candidate - junior or senior - is the appreciation for and practice of collaboration.
For a junior that will - because of lack of necessary opportunity mostly - be a question of our estimate of their aptitude and inclination.
For a senior things are more interesting. One of the most undervalued skills for a senior programmer that we constantly look for is how good they are at - and appreciate practicing - collaboration. Really good senior programmers know this themselves and naturally reflect on how they do it, how it can be done and what challenges there are. A senior who seems nonplussed when asked a question on collaboration or challenges in that area - or who dismisses the question will usually not last long in a process with me. We really intend for the ambiguity of the word "practice" here. What we mean is that a good senior candidate will both have practiced in the sense of "done the work" and they will have collaborated and be able to tell a story. They will also have tried "practicing getting better at it" - at least by reflecting. Best case they have actually attempted just that - becoming better at collaborating by practice, by repeatedly trying things.
Collaboration is a vital skill and also something that is an undertaking of lifelong learning. People who are great collaborators will not only reflect upon their own efforts or where they are and want to go but also see how others are struggling, what a potential "nudge" in the right direction will be and also when the time is right to apply that nudge. Great collaborators will make colleagues and teams "just work" and not only that - they will soon contribute to a sustainable, productive pace or show resilience in times of trouble. Invaluable and - the way we see it - quite easily comparable to great coding skills or deep technical insight. At Funnel - among other things - we look for both of these sets of skills (technical excellence and collaboration) as well as a genuine interest in developing, discussing and practicing both. Being great at only one and not the other will not get you hired.