def METHOD_NAME(output):
    """Normalize DTrace output for comparison.
    DTrace keeps a per-CPU buffer, and when showing the fired probes, buffers
    are concatenated. So if the operating system moves our thread around, the
    straight result can be "non-causal". So we add timestamps to the probe
    firing, sort by that field, then strip it from the output"""
    # When compiling with '--with-pydebug', strip '[# refs]' debug output.
    output = re.sub(r"\[[0-9]+ refs\]", "", output)
    try:
        result = [
            row.split("\t")
            for row in output.splitlines()
            if row and not row.startswith('#')
        ]
        result.sort(key=lambda row: int(row[0]))
        result = [row[1] for row in result]
        return "\n".join(result)
    except (IndexError, ValueError):
        raise AssertionError(
            "tracer produced unparseable output:\n{}".format(output)
        )