fix source prefix

pipeline.py

@@ -125,9 +125,9 @@ class QASRL_Pipeline(Text2TextGenerationPipeline):
     def _get_source_prefix(self, predicate_type: Optional[str]):
         if not self.is_t5_model or self.data_args.source_prefix is None:
             return ''
-        if "Generate QAs for <predicate_type> QASRL: " in self.data_args.source_prefix:
+        if "<predicate_type>" in self.data_args.source_prefix:
             if predicate_type is None:
-                raise ValueError("source_prefix includes 'Generate QAs for <predicate_type> QASRL: ' but input has no `predicate_type`.")
+                raise ValueError("source_prefix includes '<predicate_type>' but input has no `predicate_type`.")
             if self.data_args.source_prefix == "Generate QAs for <predicate_type> QASRL: ": # backwrad compatibility - "Generate QAs for <predicate_type> QASRL: " alone was a sign for a longer prefix 
                 return f"Generate QAs for {predicate_type} QASRL: "
             else: