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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 find_annotations(data, retriever=None):
 """Find annotation configuration files for vcfanno, using pre-installed inputs. Creates absolute paths for user specified inputs and finds locally installed defaults. Default annotations: - gemini for variant pipelines - somatic for variant tumor pipelines - rnaedit for RNA-seq variant calling """

    conf_files = dd.get_vcfanno(data)
    if not isinstance(conf_files, (list, tuple)):
        conf_files = [conf_files]
    for c in _default_conf_files(data, retriever):
        if c not in conf_files:
            conf_files.append(c)
    conf_checkers = {"gemini": annotate_gemini, "somatic": _annotate_somatic}
    out = []
    annodir = os.path.normpath(os.path.join(os.path.dirname(dd.get_ref_file(data)), os.pardir, "config", "vcfanno"))
    if not retriever:
        annodir = os.path.abspath(annodir)
    for conf_file in conf_files:
        if objectstore.is_remote(conf_file) or (os.path.exists(conf_file) and os.path.isfile(conf_file)):
            conffn = conf_file
        elif not retriever:
            conffn = os.path.join(annodir, conf_file + ".conf")
        else:
            conffn = conf_file + ".conf"
        luafn = "%s.lua" % utils.splitext_plus(conffn)[0]
        if retriever:
            conffn, luafn = [(x if objectstore.is_remote(x) else None)
                             for x in retriever.add_remotes([conffn, luafn], data["config"])]
        if not conffn:
            pass
        elif conf_file in conf_checkers and not conf_checkers[conf_file](data, retriever):
            logger.warn("Skipping vcfanno configuration: %s. Not all input files found." % conf_file)
        elif not objectstore.file_exists_or_remote(conffn):
            build = dd.get_genome_build(data)
            CONF_NOT_FOUND = (
                "The vcfanno configuration {conffn} was not found for {build}, skipping.")
            logger.warn(CONF_NOT_FOUND.format(**locals()))
        else:
            out.append(conffn)
            if luafn and objectstore.file_exists_or_remote(luafn):
                out.append(luafn)
    return out