tests and error catching for double executions

test/completion/arrays.py

@@ -98,7 +98,7 @@ u1.real
 u1.upper
 
 # -----------------
-# should fail
+# should fail (return nothing)
 # -----------------
 (f, g) = (1,)
 #? ['imag']

test/completion/functions.py

@@ -38,3 +38,9 @@ def variable_rename(param):
 
 #? ['imag']
 variable_rename(1).imag
+
+# double execution -> shouldn't work (and throw no error)
+#? []
+variable_rename(list())().
+#? []
+variable_rename(1)().