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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 create_environment(component_config):
 """ Create a modified environment. Arguments component_config - The configuration for a component. """

    ret = os.environ.copy()
    for env in component_config.get_list("dp.env_list"):
        real_env = env.upper()
        value = os.environ.get(real_env)
        value = _prepend_env(component_config, env, value)
        value = _append_env(component_config, env, value)
        _apply_change(ret, real_env, value, component_config)
    return ret