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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 delete_date(self, date):
 """ Remove the date line from the textual representation. This doesn't remove any entry line. """

        self.lines = [
            line for line in self.lines
            if not isinstance(line, DateLine) or line.date != date
        ]

        self.lines = trim(self.lines)