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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 set_environment_var_options(config, env=None, prefix='CONFPY'):
 """Set any configuration options which have an environment var set. Args: config (confpy.core.config.Configuration):
 A configuration object which has been initialized with options. env (dict):
 Optional dictionary which contains environment variables. The default is os.environ if no value is given. prefix (str):
 The string prefix prepended to all environment variables. This value will be set to upper case. The default is CONFPY. Returns: confpy.core.config.Configuration: A configuration object with environment variables set. The pattern to follow when setting environment variables is: <PREFIX>_<SECTION>_<OPTION> Each value should be upper case and separated by underscores. """

    env = env or os.environ
    for section_name, section in config:

        for option_name, _ in section:

            var_name = '{0}_{1}_{2}'.format(
                prefix.upper(),
                section_name.upper(),
                option_name.upper(),
            )
            env_var = env.get(var_name)
            if env_var:

                setattr(section, option_name, env_var)

    return config