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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 _install_container_bcbio_system(datadir):
 """Install limited bcbio_system.yaml file for setting core and memory usage. Adds any non-specific programs to the exposed bcbio_system.yaml file, only when upgrade happening inside a docker container. """

    base_file = os.path.join(datadir, "config", "bcbio_system.yaml")
    if not os.path.exists(base_file):
        return
    expose_file = os.path.join(datadir, "galaxy", "bcbio_system.yaml")
    expose = set(["memory", "cores", "jvm_opts"])
    with open(base_file) as in_handle:
        config = yaml.safe_load(in_handle)
    if os.path.exists(expose_file):
        with open(expose_file) as in_handle:
            expose_config = yaml.safe_load(in_handle)
    else:
        expose_config = {"resources": {}}
    for pname, vals in config["resources"].items():
        expose_vals = {}
        for k, v in vals.items():
            if k in expose:
                expose_vals[k] = v
        if len(expose_vals) > 0 and pname not in expose_config["resources"]:
            expose_config["resources"][pname] = expose_vals
    if expose_file and os.path.exists(os.path.dirname(expose_file)):
        with open(expose_file, "w") as out_handle:
            yaml.safe_dump(expose_config, out_handle, default_flow_style=False, allow_unicode=False)
    return expose_file