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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 getPhysicalMinimum(self,chn=None):
 """ Returns the minimum physical value of signal edfsignal. Parameters chn : int channel number Examples -------- True """

        if chn is not None:
            if 0 <= chn < self.signals_in_file:
                return self.physical_min(chn)
            else:
                return 0
        else:
            physMin = np.zeros(self.signals_in_file)
            for i in np.arange(self.signals_in_file):
                physMin[i] = self.physical_min(i)
            return physMin