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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 import_env(*envs):
    'import environment variables from host'
    for env in envs:
        parts = env.split(':', 1)
        if len(parts) == 1:
            export_as = env
        else:
            env, export_as = parts
        env_val = os.environ.get(env)
        if env_val is not None:
            yield '{}={}'.format(export_as, shlex.quote(env_val))