Implemented the in operator in a very simple fashion: It returns nothing.

jedi/evaluate/precedence.py

@@ -157,6 +157,8 @@ def _element_calculate(evaluator, left, operator, right):
         except TypeError:
             # Could be True or False.
             return [true_obj, false_obj]
+    elif operator == 'in':
+        return []
 
     def check(obj):
         """Checks if a Jedi object is either a float or an int."""

jedi/parser/tree.py

@@ -400,6 +400,7 @@ class Simple(Base):
     def get_code(self):
         return "".join(c.get_code() for c in self.children)
 
+    @Python3Method
     def name_for_position(self, position):
         for c in self.children:
             if isinstance(c, Leaf):

test/completion/precedence.py

@@ -68,6 +68,19 @@ i += 1
 #? int()
 x[i]
 
+# -----------------
+# in
+# -----------------
+
+if 'X' in 'Y':
+    a = 3
+else:
+    a = ''
+# For now don't really check for truth values. So in should return both
+# results.
+#? str() int()
+a
+
 # -----------------
 # for flow assignments
 # -----------------