assignTeam(ident uid, ident id, ident studentId, ident teamId) {
assume exists /account[uid]/tutor[id]/group[/exercise[id]/student[studentId]/group];
# implies the existence of the student, the exercise, the group and enough rights by a tutor account
assume not exists /exercise[id]/student[studentId]/team;
insert /exercise[id]/student[studentId]/team teamId;
}