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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def load_array(self, fn, name):
 """ Can only load files that were saved in the 'raw' format. Loads previously computed field 'name' from file Valid names are 'mag', 'direction', 'uca', 'twi' """


        if os.path.exists(fn + '.npz'):
            array = np.load(fn + '.npz')
            try:
                setattr(self, name, array['arr_0'])
            except Exception, e:
                print e
            finally:
                array.close()

        else:
            raise RuntimeError("File %s does not exist." % (fn + '.npz'))