Return value from main rather than print

We only really want to print if we are running the module as a script.
It's nice to allow `main` to be imported and used from other code, and
that code probably wants a returned value rather than having to read
from stdout.

pdf_table_extraction_and_ocr.org

@@ -905,15 +905,15 @@ def main(files):
             cv2.imwrite(table_filepath, table)
         if tables:
             results.append((f, files))
-
-    for image_filename, table_filenames in results:
-        print("\n".join(table_filenames))
-
+    # Results is [[<input image>, [<images of detected tables>]]]
+    return results
 
 if __name__ == "__main__":
     args = parser.parse_args()
     files = args.files
-    main(files)
+    results = main(files)
+    for image, tables in results:
+        print("\n".join(tables))
 #+END_SRC
 
 *** table_ocr/extract_cells/

table_ocr/extract_tables/__main__.py

@@ -28,12 +28,12 @@ def main(files):
             cv2.imwrite(table_filepath, table)
         if tables:
             results.append((f, files))
-
-    for image_filename, table_filenames in results:
-        print("\n".join(table_filenames))
-
+    # Results is [[<input image>, [<images of detected tables>]]]
+    return results
 
 if __name__ == "__main__":
     args = parser.parse_args()
     files = args.files
-    main(files)
+    results = main(files)
+    for image, tables in results:
+        print("\n".join(tables))