text: import Ember from 'ember';
  
  const get = Ember.get;
  const {
    computed,
    typeOf,
    A: emberArray
  } = Ember;
  
  export function add(...dependentKeys) {
    const computedFunc = computed({
      get() {
        const values = dependentKeys.map((dependentKey) => {
          const value = get(this, dependentKey);
  
          if (typeOf(value) !== 'number') {
            return;
          }
  
          return value;
        });
  
        return emberArray(values).compact().reduce((prev, curr) => {
          return prev + curr;
        });
      }
    });
  
    return computedFunc.property.apply(computedFunc, dependentKeys);
  }
  