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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 build_header(self, title):
 """Generate the header for the Markdown file."""

        header = ['---',
                  'title: ' + title,
                  'author(s): ' + self.user,
                  'tags: ',
                  'created_at: ' + str(self.date_created),
                  'updated_at: ' + str(self.date_updated),
                  'tldr: ',
                  'thumbnail: ',
                  '---']

        self.out = header + self.out