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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 _get_go2nt(goids, go2nt_all):
 """Get user go2nt using main GO IDs, not alt IDs."""

    go_nt_list = []
    goids_seen = set()
    for goid_usr in goids:
        ntgo = go2nt_all[goid_usr]
        goid_main = ntgo.id
        if goid_main not in goids_seen:
            goids_seen.add(goid_main)
            go_nt_list.append((goid_main, ntgo))
    return go_nt_list