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
Create a modified environment.

    Arguments
    component_config - The configuration for a component.