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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 get_boto_session( region, aws_access_key_id=None, aws_secret_access_key=None, aws_session_token=None ):
 """Get a boto3 session."""

    return boto3.session.Session(
        region_name=region,
        aws_secret_access_key=aws_secret_access_key,
        aws_access_key_id=aws_access_key_id,
        aws_session_token=aws_session_token
    )