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to bulk fetch team members, use the /searchPeople endpoint
to bulk fetch people, use the /searchTeams endpoint
To link people to teams, use (e.g.) getTeamsMemberships (provide list of Teams, gets people for each team) or getPeopleMemberships (provide list of people, get teams of which they are members). Recommended done in batches of <1000 people or teams to reduce api gateway load (Requires automation of api calls to cycle through a full list of people or teams, noting gateway limit of 20 requests per second for all calls)
to bulk fetch team hierarchy, use getTeams, using same approach above
to bulk fetch tags, use getPeopleTags and get TeamTags