code: func NodeSelectorRequirementKeysExistInNodeSelectorTerms(reqs []v1.NodeSelectorRequirement, terms []v1.NodeSelectorTerm) bool {
  	for _, req := range reqs {
  		for _, term := range terms {
  			for _, r := range term.MatchExpressions {
  				if r.Key == req.Key {
  					return true
  				}
  			}
  		}
  	}
  	return false
  }
docs: // NodeSelectorRequirementKeysExistInNodeSelectorTerms checks if a NodeSelectorTerm with key is already specified in terms