<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def header(self, headers):
 """Add headers to the email :param value: A list of Header objects or a dict of header key/values :type value: Header, list(Header), dict """

        if isinstance(headers, list):
            for h in headers:
                self.add_header(h)
        else:
            self.add_header(headers)