diff --git a/jedi/evaluate/__init__.py b/jedi/evaluate/__init__.py
index de78f2f5..0de778be 100644
--- a/jedi/evaluate/__init__.py
+++ b/jedi/evaluate/__init__.py
@@ -291,7 +291,7 @@ class Evaluator(object):
             types = set([element])  # TODO this is no real evaluation.
         elif element.type == 'expr_stmt':
             types = self.eval_statement(element)
-        elif element.type == 'power' or element.type == 'atom_expr':
+        elif element.type in ('power', 'atom_expr'):
             types = self._eval_atom(element.children[0])
             for trailer in element.children[1:]:
                 if trailer == '**':  # has a power operation.
diff --git a/jedi/evaluate/analysis.py b/jedi/evaluate/analysis.py
index 87c961dd..7b4b0acc 100644
--- a/jedi/evaluate/analysis.py
+++ b/jedi/evaluate/analysis.py
@@ -174,7 +174,7 @@ def _check_for_exception_catch(evaluator, jedi_obj, exception, payload=None):
     def check_hasattr(node, suite):
         try:
             assert suite.start_pos <= jedi_obj.start_pos < suite.end_pos
-            assert node.type == 'power' or node.type == 'atom_expr'
+            assert node.type in ('power', 'atom_expr')
             base = node.children[0]
             assert base.type == 'name' and base.value == 'hasattr'
             trailer = node.children[1]
diff --git a/jedi/evaluate/dynamic.py b/jedi/evaluate/dynamic.py
index 6ca429fe..8cd08641 100644
--- a/jedi/evaluate/dynamic.py
+++ b/jedi/evaluate/dynamic.py
@@ -89,8 +89,7 @@ def search_function_call(evaluator, func):
                     parent = parent.parent
 
                 trailer = None
-                if tree.is_node(parent, 'power') or \
-                        tree.is_node(parent, 'atom_expr'):
+                if tree.is_node(parent, 'power', 'atom_expr'):
                     for t in parent.children[1:]:
                         if t == '**':
                             break
diff --git a/jedi/evaluate/finder.py b/jedi/evaluate/finder.py
index db9561c3..5003848c 100644
--- a/jedi/evaluate/finder.py
+++ b/jedi/evaluate/finder.py
@@ -448,7 +448,7 @@ def check_flow_information(evaluator, flow, search_name, pos):
 
 def _check_isinstance_type(evaluator, element, search_name):
     try:
-        assert element.type == 'power' or element.type == 'atom_expr'
+        assert element.type in ('power', 'atom_expr')
         # this might be removed if we analyze and, etc
         assert len(element.children) == 2
         first, trailer = element.children
diff --git a/jedi/evaluate/helpers.py b/jedi/evaluate/helpers.py
index 86eec876..76d1796e 100644
--- a/jedi/evaluate/helpers.py
+++ b/jedi/evaluate/helpers.py
@@ -88,7 +88,7 @@ def call_of_name(name, cut_own_trailer=False):
             return name
 
     power = par.parent
-    if (tree.is_node(power, 'power') or tree.is_node(power, 'atom_expr')) \
+    if tree.is_node(power, 'power', 'atom_expr') \
             and power.children[0] != name \
             and not (power.children[-2] == '**' and
                      name.start_pos > power.children[-1].start_pos):
diff --git a/jedi/parser/tree.py b/jedi/parser/tree.py
index 867d8cde..89c37841 100644
--- a/jedi/parser/tree.py
+++ b/jedi/parser/tree.py
@@ -1342,7 +1342,7 @@ def _defined_names(current):
             names += _defined_names(child)
     elif is_node(current, 'atom'):
         names += _defined_names(current.children[1])
-    elif is_node(current, 'power') or is_node(current, 'atom_expr'):
+    elif is_node(current, 'power', 'atom_expr'):
         if current.children[-2] != '**':  # Just if there's no operation
             trailer = current.children[-1]
             if trailer.children[0] == '.':