Filter entities by name when extracting data from Arkindex

Closes #134 (closed)

dan/datasets/extract/__init__.py

@@ -83,7 +83,14 @@ def add_extract_parser(subcommands) -> None:
 
     # Optional arguments.
     parser.add_argument(
-        "--load-entities", action="store_true", help="Extract text with their entities."
+        "--load-entities",
+        action="store_true",
+        help="Extract text with their entities.",
+    )
+    parser.add_argument(
+        "--only-entities",
+        action="store_true",
+        help="Remove all text that does not belong to the tokens.",
     )
     parser.add_argument(
         "--allow-unknown-entities",