Add ability to run without template for simpler api

Signed-off-by: elronbandel <elronbandel@gmail.com>

src/unitxt/standard.py

@@ -145,7 +145,7 @@ def verify(self):
 
         if self.template is None:
             raise ValueError(
-                "You must set in the recipe either `template`, `template_card_index` or `templates`."
+                "You must set in the recipe either `template`, `template_card_index`."
             )
 
         if isinstance(self.template, list):
@@ -411,9 +411,13 @@ def prepare(self):
         assert (
             self.template_card_index is None or self.template is None
         ), f"Specify either template ({self.template}) or template_card_index ({self.template_card_index}) but not both"
-        assert not (
-            self.template_card_index is None and self.template is None
-        ), "Specify either template or template_card_index in card"
+
+        if self.template_card_index is None and self.template is None:
+            self.template_card_index = 0
+            logger.warning(
+                "Template was not specified in recipe, using template_card_index=0 by default."
+            )
+
         if self.template_card_index is not None:
             try:
                 self.template = self.card.templates[self.template_card_index]

tests/library/test_api.py

@@ -13,6 +13,12 @@
 class TestAPI(UnitxtTestCase):
     maxDiff = None
 
+    def test_load_dataset_without_template(self):
+        dataset = load_dataset(
+            "card=cards.stsb",
+        )
+        self.assertEqual(len(dataset["train"]), 282)
+
     def test_load_dataset(self):
         dataset = load_dataset(
             "card=cards.stsb,template=templates.regression.two_texts.simple,max_train_instances=5,max_validation_instances=5,max_test_instances=5",