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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_dbf(self, shapefile_name):

 """
 Attempts to load file with .dbf extension as both lower and upper case
 """

        dbf_ext = 'dbf'
        try:
            self.dbf = open("%s.%s" % (shapefile_name, dbf_ext), "rb")
        except IOError:
            try:
                self.dbf = open("%s.%s" % (shapefile_name, dbf_ext.upper()), "rb")
            except IOError:
                pass