Easy warning fixups for mypy (pandas-dev#27402)

Author: WillAyd

pandas/core/computation/pytables.py

@@ -90,17 +90,15 @@ def pr(left, right):
 
             k = klass
             if isinstance(left, ConditionBinOp):
-                if isinstance(left, ConditionBinOp) and isinstance(
-                    right, ConditionBinOp
-                ):
+                if isinstance(right, ConditionBinOp):
                     k = JointConditionBinOp
                 elif isinstance(left, k):
                     return left
                 elif isinstance(right, k):
                     return right
 
             elif isinstance(left, FilterBinOp):
-                if isinstance(left, FilterBinOp) and isinstance(right, FilterBinOp):
+                if isinstance(right, FilterBinOp):
                     k = JointFilterBinOp
                 elif isinstance(left, k):
                     return left

pandas/io/json/_normalize.py

@@ -112,7 +112,7 @@ def nested_to_record(
 
 
 def json_normalize(
-    data: List[Dict],
+    data: Union[Dict, List[Dict]],
     record_path: Optional[Union[str, List]] = None,
     meta: Optional[Union[str, List]] = None,
     meta_prefix: Optional[str] = None,
@@ -280,8 +280,6 @@ def _pull_field(js, spec):
     lengths = []
 
     meta_vals = defaultdict(list)  # type: DefaultDict
-    if not isinstance(sep, str):
-        sep = str(sep)
     meta_keys = [sep.join(val) for val in meta]
 
     def _recursive_extract(data, path, seen_meta, level=0):