minor internal changes

Author: parikshit14

src/modelspec/base_types.py

@@ -278,7 +278,7 @@ def from_bson_file(cls, filename: str) -> "Base":
         Returns:
             An modelspec :class:`.Base` for this BSON
         """
-        with open("document.bson", "rb") as infile:
+        with open(filename, "rb") as infile:
             data_encoded = infile.read()
             d = bson.decode(data_encoded)
             return cls.from_dict(d)