Adds comment

packages/medusa/src/models/customer.js

@@ -13,7 +13,7 @@ class CustomerModel extends BaseModel {
     email: { type: String, required: true, unique: true },
     first_name: { type: String, required: true },
     last_name: { type: String, required: true },
-    billingAddress: { type: AddressSchema },
+    billing_address: { type: AddressSchema },
     password_hash: { type: String },
     metadata: { type: mongoose.Schema.Types.Mixed, default: {} },
   }

packages/medusa/src/services/cart.js

@@ -172,7 +172,10 @@ class CartService extends BaseService {
   }
 
   /**
-   *
+   * Adds a line item to the cart.
+   * @param {string} cartId - the id of the cart that we will add to
+   * @param {LineItem} lineItem - the line item to add.
+   * @retur {Promise} the result of the update operation
    */
   async addLineItem(cartId, lineItem) {
     const validatedLineItem = this.validateLineItem_(lineItem)