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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 invite(self, users, role, expiration=1440):
 """ A group administrator can invite users to join their group using the Invite to Group operation. This creates a new user invitation, which the users accept or decline. The role of the user and the invitation expiration date can be set in the invitation. A notification is created for the user indicating that they were invited to join the group. Available only to authenticated users. Inputs: users - A comma separated list of usernames to be invited to the group. If a user is already a member of the group or an invitation has already been sent, the call still returns a success. Example: users=regularusername1,regularusername2 role	- Allows administrators to set the user's role in the group Roles are: group_member: Ability to view and share items with group. group_admin: In addition to viewing and sharing items, the group_admin has the same capabilities as the group owner-invite users to the group, accept or decline group applications, delete content, and remove users. expiration - Expiration date on the invitation can be set for one day, three days, one week, or two weeks, in minutes. Default is 1440 """

        params = {
            "f" : "json",
            "users" : users,
            "role" : role,
            "expiration" : expiration
        }
        return self._post(url=self._url + "/invite",
                             securityHandler=self._securityHandler,
                             param_dict=params,
                             proxy_url=self._proxy_url,
                             proxy_port=self._proxy_port)