code: function removeMissingPurchasesByPredicate( existingPurchases, newPurchases, predicate ) {
  	return existingPurchases.filter( purchase => {
  		if ( matches( predicate )( purchase ) && find( newPurchases, { ID: purchase.ID } ) ) {
  			// this purchase is present in the new array
  			return true;
  		}
  
  		if ( ! matches( predicate )( purchase ) ) {
  			// only overwrite remove purchases that match the predicate
  			return true;
  		}
  
  		// the purchase doesn't match the predicate or is missing from the array of new purchases
  		return false;
  	} );
  }
docs: Removes purchases that are missing from the new purchases array and match the given predicate.
  
  @param {array} existingPurchases - an array of purchases in the store
  @param {array} newPurchases - an array of purchases fetched from the API
  @param {object} predicate - the predicate to check before removing the item from the array.
  @return {array} An array of purchases