diff --git a/src/json_parser.py b/src/json_parser.py
index eec02be..f0f9c8b 100644
--- a/src/json_parser.py
+++ b/src/json_parser.py
@@ -12,8 +12,13 @@ def _get_fields(json_data: dict) -> list[str]:
     Returns:
         list[str]: A list of field names extracted from the JSON data.
     """
-    attributes = json_data["conceptCodes"][0]["attributes"]
-    namelist = [attribute["attributeName"] for attribute in attributes]
+    namelist = []
+    for attr in json_data["conceptCodes"]:
+        for name in attr["attributes"]:
+            if name["attributeName"] not in namelist:
+                namelist.append(name["attributeName"])
+            
+        
     return namelist
 
 def parse_json(json_file: Path) -> list[str]:
@@ -32,6 +37,6 @@ def parse_json(json_file: Path) -> list[str]:
     try:
         with open(json_file, "r") as f:
             json_data = json.load(f)
-    except json.JSONDecodeError as e:
+    except json.JSONDecodeError:
         raise click.FileError(json_file, "Not a valid JSON file.")
     return _get_fields(json_data)
\ No newline at end of file