diff --git a/trains/model.py b/trains/model.py
index 806aefb7..384254fa 100644
--- a/trains/model.py
+++ b/trains/model.py
@@ -6,7 +6,7 @@ from tempfile import mkdtemp, mkstemp
 
 import pyparsing
 import six
-from typing import List, Dict, Union, Optional, TYPE_CHECKING, Sequence
+from typing import List, Dict, Union, Optional, Mapping, TYPE_CHECKING, Sequence
 
 from .backend_api import Session
 from .backend_api.services import models
@@ -446,7 +446,7 @@ class InputModel(Model):
         weights_url,  # type: str
         config_text=None,  # type: Optional[str]
         config_dict=None,  # type: Optional[dict]
-        label_enumeration=None,  # type: Optional[Dict[str, int]]
+        label_enumeration=None,  # type: Optional[Mapping[str, int]]
         name=None,  # type: Optional[str]
         tags=None,  # type: Optional[List[str]]
         comment=None,  # type: Optional[str]
@@ -598,17 +598,27 @@ class InputModel(Model):
     def load_model(cls, weights_url, load_archived=False):
         # type: (str, bool) -> InputModel
         """
-        Load an already registered model based on a pre-existing model file (link must be valid).
+        Load an already registered model based on a pre-existing model file (link must be valid). If the url to the
+        weights file already exists, the returned object is a Model representing the loaded Model. If no registered
+        model with the specified url is found, ``None`` is returned.
 
-        If the url to the weights file already exists, the returned object is a Model representing the loaded Model
-        If there could not be found any registered model Model with the specified url, None is returned.
+        :param weights_url: The valid url for the weights file (string).
 
-        :param weights_url: valid url for the weights file (string).
-            examples: "https://domain.com/file.bin" or "s3://bucket/file.bin" or "file:///home/user/file.bin".
-            NOTE: if a model with the exact same URL exists, it will be used, and all other arguments will be ignored.
-        :param bool load_archived: If True return registered Model with even if they are archived,
-            otherwise archived models are ignored,
-        :return Model: InputModel object or None if no model could be found
+            Examples:
+
+            .. code-block:: py
+
+                "https://domain.com/file.bin" or "s3://bucket/file.bin" or "file:///home/user/file.bin".
+
+            .. note::
+                If a model with the exact same URL exists, it will be used, and all other arguments will be ignored.
+
+        :param bool load_archived: Load archived models?
+
+            - ``True`` - Load the registered Model, if it is archived.
+            - ``False`` - Ignore archive models.
+
+        :return: InputModel object, or ``None`` if no model could be found.
         """
         weights_url = StorageHelper.conform_url(weights_url)
         if not weights_url:
@@ -641,7 +651,7 @@ class InputModel(Model):
 
     @classmethod
     def empty(cls, config_text=None, config_dict=None, label_enumeration=None):
-        # type: (Optional[str], Optional[dict], Optional[Dict[str, int]]) -> InputModel
+        # type: (Optional[str], Optional[dict], Optional[Mapping[str, int]]) -> InputModel
         """
         Create an empty model object. Later, you can assign a model to the empty model object.
 
@@ -661,6 +671,8 @@ class InputModel(Model):
                     'background': 0,
                     'person': 1
                }
+
+        :return: Empty model object.
         """
         design = cls._resolve_config(config_text=config_text, config_dict=config_dict)
 
@@ -822,7 +834,7 @@ class OutputModel(BaseModel):
 
     @labels.setter
     def labels(self, value):
-        # type: (Dict[str, int]) -> None
+        # type: (Mapping[str, int]) -> None
         """
         Set the label enumeration.
 
@@ -850,7 +862,7 @@ class OutputModel(BaseModel):
         task=None,  # type: Optional[Task]
         config_text=None,  # type: Optional[str]
         config_dict=None,  # type: Optional[dict]
-        label_enumeration=None,  # type: Optional[Dict[str, int]]
+        label_enumeration=None,  # type: Optional[Mapping[str, int]]
         name=None,  # type: Optional[str]
         tags=None,  # type: Optional[List[str]]
         comment=None,  # type: Optional[str]
@@ -914,7 +926,7 @@ class OutputModel(BaseModel):
         )
         if base_model_id:
             try:
-                _base_model = InputModel(base_model_id)._get_base_model()
+                _base_model = self._task._get_output_model(model_id=base_model_id)
                 _base_model.update(
                     labels=self._floating_data.labels,
                     design=self._floating_data.design,
@@ -922,8 +934,9 @@ class OutputModel(BaseModel):
                     project_id=self._task.project,
                     name=self._floating_data.name or task.name,
                     comment=('{}\n{}'.format(_base_model.comment, self._floating_data.comment)
-                             if _base_model.comment and self._floating_data.comment else
-                             (_base_model.comment or self._floating_data.comment)),
+                             if (_base_model.comment and self._floating_data.comment and
+                                 self._floating_data.comment not in _base_model.comment)
+                             else (_base_model.comment or self._floating_data.comment)),
                     tags=self._floating_data.tags,
                     framework=self._floating_data.framework,
                     upload_storage_uri=self._floating_data.upload_storage_uri
@@ -1245,10 +1258,11 @@ class OutputModel(BaseModel):
         :param dict config_dict: The configuration as a dictionary. Specify ``config_text`` or ``config_dict``,
             but not both.
 
-        :return bool: The status of the update.
+        :return: The status of the update.
 
             - ``True`` - Update successful.
             - ``False`` - Update not successful.
+
         """
         if not self._validate_update():
             return False
@@ -1269,7 +1283,7 @@ class OutputModel(BaseModel):
         return result
 
     def update_labels(self, labels):
-        # type: (Dict[str, int]) -> Optional[Waitable]
+        # type: (Mapping[str, int]) -> Optional[Waitable]
         """
         Update the label enumeration.