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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 __sethead(self, access_token):
 """Set HTTP header."""

        self.access_token = access_token
        now = calendar.timegm(datetime.datetime.now().timetuple())
        self.expiration = now + 1800
        self.head = {"Authorization": "Bearer %s" % access_token,
                     "User-Agent": self.user_agent
                     }