add Message.preview()

csst_common/pipeline.py

@@ -289,6 +289,13 @@ class Message:
             for d in dlist:
                 f.write(self.dict2msg(d) + "\n")
 
+    def preview(self, dlist: list[dict]) -> str:
+        """Preview messages."""
+        s = ""
+        for d in dlist:
+            s += self.dict2msg(d) + "\n"
+        print(s)
+
     @staticmethod
     def dict2msg(d: dict):
         """Convert `dict` to JSON format string."""