<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _chk_hdrgoids(hdrgos):
 """Check that hdrgo set is a set of GO IDs."""

        goid = next(iter(hdrgos))
        if isinstance(goid, str) and goid[:3] == "GO:":
            return
        assert False, "HDRGOS DO NOT CONTAIN GO IDs: {E}".format(E=goid)