Fix possible bug within serialize_possible_ml_model function (#103)

* fix the usage of `upper`

* remove `str` field from getting into `transporting` process

Author: AHReccese

pymilo/chains/ensemble_chain.py

@@ -118,6 +118,8 @@ def serialize_possible_ml_model(possible_ml_model):
     :type possible_ml_model: obj
     :return: tuple(bool, whether itself or dict)
     """
+    if isinstance(possible_ml_model, str):
+        return False, possible_ml_model
     ml_category, transporter = get_transporter(possible_ml_model)
     if transporter is not None:
         return True, {

pymilo/chains/util.py

@@ -29,8 +29,9 @@ def get_concrete_transporter(model):
     :return: tuple(ML_MODEL_CATEGORY, transporter function)
     """
     if isinstance(model, str):
-        if model.upper() in MODEL_TYPE_TRANSPORTER.keys():
-            return model, MODEL_TYPE_TRANSPORTER[model]
+        upper_model = model.upper()
+        if upper_model in MODEL_TYPE_TRANSPORTER.keys():
+            return upper_model, MODEL_TYPE_TRANSPORTER[upper_model]
 
     if is_linear_model(model):
         return "LINEAR_MODEL", transport_linear_model