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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 checksum(self):
 """Grab checksum string """

        md5sum, md5sum64, = [], []
        for line in self.SLACKBUILDS_TXT.splitlines():
            if line.startswith(self.line_name):
                sbo_name = line[17:].strip()
            if line.startswith(self.line_md5_64):
                if sbo_name == self.name and line[26:].strip():
                    md5sum64 = line[26:].strip().split()
            if line.startswith(self.line_md5):
                if sbo_name == self.name and line[19:].strip():
                    md5sum = line[19:].strip().split()
        return self._select_md5sum_arch(md5sum, md5sum64)