change: enable consider-merging-isinstance Pylint check (#932)

Note that this commit will also enable simplifiable-if-statement, as
there are no code changes needed for it.

Author: knakad

.pylintrc

@@ -91,13 +91,11 @@ disable=
     useless-object-inheritance, # TODO: Remove unnecessary imports
     cyclic-import, # TODO: Resolve cyclic imports
     no-self-use, # TODO: Convert methods to functions where appropriate
-    consider-merging-isinstance, # TODO: Merge isinstance where appropriate
     consider-using-in, # TODO: Consider merging comparisons with "in"
     too-many-public-methods, # TODO: Resolve
     ungrouped-imports, # TODO: Group imports
     consider-using-ternary, # TODO: Consider ternary expressions
     chained-comparison, # TODO: Simplify chained comparison between operands
-    simplifiable-if-statement, # TODO: Simplify ifs
     too-many-branches, # TODO: Simplify or ignore as appropriate
     missing-docstring, # TODO: Fix missing docstring
 

src/sagemaker/tuner.py

@@ -307,7 +307,7 @@ def fit(self, inputs=None, job_name=None, include_cls_metadata=False, **kwargs):
             **kwargs: Other arguments needed for training. Please refer to the ``fit()`` method of the associated
                 estimator to see what other arguments are needed.
         """
-        if isinstance(inputs, list) or isinstance(inputs, RecordSet):
+        if isinstance(inputs, (list, RecordSet)):
             self.estimator._prepare_for_training(inputs, **kwargs)
         else:
             self.estimator._prepare_for_training(job_name)