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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 ReadDataFile(self):
 """ Reads the contents of the Comtrade .dat file and store them in a private variable. For accessing a specific channel data, see methods getAnalogData and getDigitalData. """

        if os.path.isfile(self.filename[0:-4] + '.dat'):
            filename = self.filename[0:-4] + '.dat'
    
        elif os.path.isfile(self.filename[0:-4] + '.DAT'):
            filename = self.filename[0:-4] + '.DAT'
        
        else:
            print "Data file File not found."
            return 0
        
        self.filehandler = open(filename,'rb')
        self.DatFileContent = self.filehandler.read()
    
        # END READING .dat FILE.
        self.filehandler.close() # Close file.        
        
        return 1