def _match_header(self):
        """
        Messages that have a header with the specified field-name (as
        defined in [RFC-822]) and that contains the specified string
        in the [RFC-822] field-body.
        """
        header = self.args["header"]
        return self.ctx.msg in header and \
           self.ctx.msg[header].lower().find(self.args['string']) != -1

    #########################################################################
    #
dataset/ETHPy150Open scanner/asimap/asimap/search.py/IMAPSearch._match_header/swapped operands of `in`