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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 _format_line(self, data, column=0, rel_line=1):
        'Formats a line from the data to be the appropriate length'
        line_length = len(data)

        if line_length > 140:
            if rel_line == 0:
                # Trim from the beginning
                data = '... %s' % data[-140:]
            elif rel_line == 1:
                # Trim surrounding the error position
                if column < 70:
                    data = '%s ...' % data[:140]
                elif column > line_length - 70:
                    data = '... %s' % data[-140:]
                else:
                    data = '... %s ...' % data[column - 70:column + 70]

            elif rel_line == 2:
                # Trim from the end
                data = '%s ...' % data[:140]

        data = unicodehelper.decode(data)
        return data