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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 create(self, dbsecgroup_id, source_cidr, port=3306):
 """ Creates a security group rule. :param str dbsecgroup_id: The ID of the security group in which this rule should be created. :param str source_cidr: The source IP address range from which access should be allowed. :param int port: The port number used by db clients to connect to the db server. This would have been specified at db instance creation time. :rtype: :class:`DBSecurityGroupRule`. """

        body = {
                "security_group_rule": {
                    "security_group_id": dbsecgroup_id,
                    "cidr": source_cidr,
                    "from_port": port,
                    "to_port": port,
                    }
                }
        return self._create("/security-group-rules", body,
                "security_group_rule")