'**SUMMARY**
Save the trainging data.
**PARAMETERS**
* *filename* - File where you want to save the data.
**RETURNS**
Nothing. None.
**EXAMPLES**
>>> f = FaceRecognizer()
>>> imgs1 = ImageSet(path/to/images_of_type1)
>>> labels1 = [0]*len(imgs1)
>>> imgs2 = ImageSet(path/to/images_of_type2)
>>> labels2 = [1]*len(imgs2)
>>> imgs3 = ImageSet(path/to/images_of_type3)
>>> labels3 = [2]*len(imgs3)
>>> imgs = imgs1 + imgs2 + imgs3
>>> labels = labels1 + labels2 + labels3
>>> f.train(imgs, labels)
>>> img = Image("some_image_of_any_of_the_above_type")
>>> print f.predict(img)
#Save New Fisher Training Data
>>> f.save("new_trainingdata.xml")'

def save(self, filename):

    if (not self.supported):
        warnings.warn('Fisher    Recognizer    is    supported    by    OpenCV    >=    2.4.4')
        return None
    self.model.save(filename)
