Added a common method signature for setting up the main parser.

common/python/nomadcore/baseclasses.py

@@ -121,6 +121,18 @@ class ParserInterface(with_metaclass(ABCMeta, object)):
         """
         pass
 
+    # @abstractmethod  # Keep this way for a file in order to avoid breaking
+    def setup_main_parser(self, version_dictionary):
+        """Setup the attribute 'main_parser' which contains the object that
+        starts the parsing from the main file. The main parser should be
+        decided based on the information contained on the given dictionary.
+
+        Args:
+            version_dictionary: Dictionary containing version information. It
+            can include the version number, run type, etc.
+        """
+        pass
+
     @abstractmethod
     def get_metainfo_filename(self):
         """This function should return the name of the metainfo file that is