diff --git a/chemrel/src/chemrel/functions/build.py b/chemrel/src/chemrel/functions/build.py
deleted file mode 100644
index 42ba553..0000000
--- a/chemrel/src/chemrel/functions/build.py
+++ /dev/null
@@ -1,33 +0,0 @@
-from functools import partial
-from pathlib import Path
-from typing import Iterable, Callable
-import spacy
-from spacy.training import Example
-from spacy.tokens import DocBin, Doc
-
-# make the factory work
-from chemrel.functions.pipeline import custom_relation_extractor
-
-
-# make the config work
-from chemrel.functions.model import build_relation_model, build_classification_layer, build_instances, build_tensors
-
-
-@spacy.registry.readers("Gold_ents_Corpus.v1")
-def create_docbin_reader(file: Path) -> Callable[["Language"], Iterable[Example]]:
-    return partial(read_files, file)
-
-
-def read_files(file: Path, nlp: "Language") -> Iterable[Example]:
-    """Custom reader that keeps the tokenization of the gold data,
-    and also adds the gold GGP annotations as we do not attempt to predict these."""
-    doc_bin = DocBin().from_disk(file)
-    docs = doc_bin.get_docs(nlp.vocab)
-    for gold in docs:
-        pred = Doc(
-            nlp.vocab,
-            words=[t.text for t in gold],
-            spaces=[t.whitespace_ for t in gold],
-        )
-        pred.ents = gold.ents
-        yield Example(pred, gold)
diff --git a/chemrel/src/chemrel/functions/parser.py b/chemrel/src/chemrel/functions/parser.py
index 1ff7606..59a44d8 100644
--- a/chemrel/src/chemrel/functions/parser.py
+++ b/chemrel/src/chemrel/functions/parser.py
@@ -26,7 +26,7 @@ def parse(json_loc: Path, train_file: Path, dev_file: Path, test_file: Path):
     """
 
     # Creating a custom extension attribute called "rel" for the Doc class and initializing it to an empty dictionary
-    Doc.set_extension("rel", default={})
+    Doc.set_extension("rel", default={}, force=True)
 
     # Creating a new Vocab object
     vocab = Vocab()