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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 is_header(self):
 """ Whether or not the cell is a header Any header cell will have "=" instead of "-" on its border. For example, this is a header cell:: +-----+ | foo | +=====+ while this cell is not:: +-----+ | foo | +-----+ Returns ------- bool Whether or not the cell is a header """

        bottom_line = self.text.split('\n')[-1]

        if is_only(bottom_line, ['+', '=']):
            return True

        return False