changes in the add_upstream path and add_domain_file_path functions

src/ansys/dpf/core/data_sources.py

@@ -425,19 +425,44 @@ def add_file_path_for_specified_result(self, filepath, key="", result_key=""):
             self, str(filepath), key, result_key
         )
 
-    def add_upstream(self, upstream_data_sources, result_key=""):
-        """Add upstream data sources.
+    def add_upstream(
+        self, upstream_data_sources: DataSources, result_key: Optional[str] = ""
+    ) -> None:
+        """Add upstream data sources to the main DataSources object.
 
         This is used to add a set of path creating an upstream for
         recursive workflows.
 
         Parameters
         ----------
-        upstream_data_sources : DataSources
+        upstream_data_sources
             Set of paths creating an upstream for recursive workflows.
 
-        result_key: str, optional
+        result_key
             Extension of the result file group with which this upstream belongs
+        Examples
+        --------
+        Add an upstream data to the main DataSources object of an expansion analysis
+
+        >>> from ansys.dpf import core as dpf
+        >>> from ansys.dpf.core import examples
+        >>>
+        >>> # Download the result files
+        >>> paths = examples.download_msup_files_to_dict()
+        >>> # Create the main DataSources object
+        >>> my_data_sources = dpf.DataSources()
+        >>> # Define the path where the main result data can be found
+        >>> my_data_sources.set_result_file_path(filepath=paths["rfrq"],  key='rfrq')
+        >>>
+        >>> # Create the DataSources object for the upstream data
+        >>> my_data_sources_upstream = dpf.DataSources()
+        >>> # Define the path where the main upstream data can be found
+        >>> my_data_sources_upstream.set_result_file_path(filepath=paths["mode"], key='mode')
+        >>> # Add the additional upstream data to the upstream DataSources object
+        >>> my_data_sources_upstream.add_file_path(filepath=paths["rst"], key='rst')
+        >>>
+        >>> # Add the upstream DataSources to the main DataSources object
+        >>> my_data_sources.add_upstream(upstream_data_sources=my_data_sources_upstream)
 
         """
         if result_key == "":