def METHOD_NAME(self):
    suffix = "_openmp" if self.spec.satisfies("+openmp") else ""
    # upstream sometimes adds tarball suffixes not part of the internal version
    elpa_version = str(self.spec.version)
    for vsuffix in ("_bugfix",):
        if elpa_version.endswith(vsuffix):  # implementation of py3.9 removesuffix
            elpa_version = elpa_version[: -len(vsuffix)]
    incdir = os.path.join(
        self.spec.prefix.include,
        "elpa{suffix}-{version}".format(suffix=suffix, version=elpa_version),
    )
    hlist = find_all_headers(incdir)
    hlist.directories = [incdir]
    return hlist