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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 get_bestnr(self, index=4.0, nhigh=3.0, null_snr_threshold=4.25,\ 		 null_grad_thresh=20., null_grad_val = 1./5.):
 		""" 		Get the BestNR statistic for each row in the table 		"""

		return [row.get_bestnr(index=index, nhigh=nhigh,
		                       null_snr_threshold=null_snr_threshold,
		                       null_grad_thresh=null_grad_thresh,
		                       null_grad_val=null_grad_val)
		        for row in self]