Small generalization to prepare for multi-argument
Small generalization to prepare for multi-argument

koryonik/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,edechter/swipl-devel