diff --git a/_test.pyx b/_test.pyx
index dfa25f0..b1536db 100644
--- a/_test.pyx
+++ b/_test.pyx
@@ -57,6 +57,8 @@ def test_the_wrapped_class():
     T = PyTestClass()
     T.x = 15
     print(T.x)
+    print("Is -10 positive?")
+    print(T.IsPositive(-10))
     T = None
     
         
diff --git a/pytestclass.pyx b/pytestclass.pyx
index 4f0ddb9..1502fee 100644
--- a/pytestclass.pyx
+++ b/pytestclass.pyx
@@ -5,10 +5,9 @@
 
 from testclass cimport TestClass
 
-
 cdef class PyTestClass:
 
-    """ 
+    """
     Cython wrapper class for C++ class TestClass
     """
 
@@ -17,23 +16,23 @@ cdef class PyTestClass:
 
     def __cinit__(PyTestClass self):
         # Initialize the "this pointer" to NULL so __dealloc__
-        # knows if there is something to deallocate. Do not 
+        # knows if there is something to deallocate. Do not
         # call new TestClass() here.
         self._thisptr = NULL
-        
+
     def __init__(PyTestClass self):
         # Constructing the C++ object might raise std::bad_alloc
         # which is automatically converted to a Python MemoryError
         # by Cython. We therefore need to call "new TestClass()" in
         # __init__ instead of __cinit__.
-        self._thisptr = new TestClass() 
+        self._thisptr = new TestClass()
 
     def __dealloc__(PyTestClass self):
-        # Only call del if the C++ object is alive, 
+        # Only call del if the C++ object is alive,
         # or we will get a segfault.
         if self._thisptr != NULL:
             del self._thisptr
-            
+
     cdef int _check_alive(PyTestClass self) except -1:
         # Beacuse of the context manager protocol, the C++ object
         # might die before PyTestClass self is reclaimed.
@@ -42,54 +41,54 @@ cdef class PyTestClass:
         if self._thisptr == NULL:
             raise RuntimeError("Wrapped C++ object is deleted")
         else:
-            return 0    
+            return 0
 
     property x:
-    
+
         # Here we use a property to expose the public member
         # x of TestClass to Python
-        
+
         def __get__(PyTestClass self):
             self._check_alive()
             return self._thisptr.x
-        
+
         def __set__(PyTestClass self, value):
             self._check_alive()
             self._thisptr.x = <int> value
 
     property y:
-    
+
         # Here we use a property to expose the public member
         # y of TestClass to Python
-    
+
         def __get__(PyTestClass self):
             self._check_alive()
             return self._thisptr.y
-    
+
         def __set__(PyTestClass self, value):
             self._check_alive()
             self._thisptr.y = <int> value
-            
-            
+
+
     def Multiply(PyTestClass self, int a, int b):
         self._check_alive()
         return self._thisptr.Multiply(a,b)
-            
-    
+
+    def IsPositive(PyTestClass self, int a):
+        self._check_alive()
+        return self._thisptr.IsPositive(a)
+
     # The context manager protocol allows us to precisely
     # control the liftetime of the wrapped C++ object. del
-    # is called deterministically and independently of 
+    # is called deterministically and independently of
     # the Python garbage collection.
 
     def __enter__(PyTestClass self):
         self._check_alive()
         return self
-    
+
     def __exit__(PyTestClass self, exc_tp, exc_val, exc_tb):
         if self._thisptr != NULL:
-            del self._thisptr 
+            del self._thisptr
             self._thisptr = NULL # inform __dealloc__
         return False # propagate exceptions
-
-
-
diff --git a/testclass.h b/testclass.h
index 2b4c80b..6228982 100644
--- a/testclass.h
+++ b/testclass.h
@@ -3,17 +3,18 @@
 
 class TestClass {
     public:
-    
+
         int x, y;
-    
+
         TestClass();
-        
+
         virtual ~TestClass();
-        
+
         inline int Multiply(int a, int b){
             return a*b;
         }
+
+        inline bool IsPositive(int a){ return a>0;}
 };
 
 #endif
-
diff --git a/testclass.pxd b/testclass.pxd
index 033e64f..8184678 100644
--- a/testclass.pxd
+++ b/testclass.pxd
@@ -2,6 +2,7 @@
 # Using a .pxd file gives us a separate namespace for
 # the C++ declarations. Using a .pxd file also allows
 # us to reuse the declaration in multiple .pyx modules.
+from libcpp cimport bool as bool_t
 
 cdef extern from "testclass.h":
 
@@ -9,8 +10,4 @@ cdef extern from "testclass.h":
         int x,y
         TestClass() except +  # NB! std::bad_alloc will be converted to MemoryError
         int Multiply(int a, int b)
-
-
-
-
-
+        bool_t IsPositive(int a)