function checkReferences(variable){// Gets references that exist in loop conditions.
var conditions=variable.references.map(toLoopCondition).filter(Boolean);if(conditions.length===0){return;}// Registers the conditions to belonging groups.
registerConditionsToGroup(conditions);// Check the conditions are modified.
var modifiers=variable.references.filter(isWriteReference);if(modifiers.length>0){updateModifiedFlag(conditions,modifiers);}/*
             * Reports the conditions which are not belonging to groups.
             * Others will be reported after all variables are done.
             */conditions.filter(isUnmodifiedAndNotBelongToGroup).forEach(report);}
Finds unmodified references which are inside of a loop condition.
Then reports the references which are outside of groups.

@param {escope.Variable} variable - A variable to report.
@returns {void}