'**SUMMARY**
Returns a new FeatureSet, with the largest area features first.
**RETURNS**
A featureset sorted based on area.
**EXAMPLE**
>>> img = Image("lenna")
>>> feats = img.findBlobs()
>>> feats = feats.sortArea()
>>> print feats[-1] # biggest blob
>>> print feats[0] # smallest blob'

def sortArea(self):

    return FeatureSet(sorted(self, key=(lambda f: f.area())))
