Fix syntax error in the ETL doctest
Fix syntax error in the ETL doctest

Egogre/xelixir,cezarykosko/xelixir,wobh/xelixir,montague/xelixir,parkerl/xelixir,elasticdog/xelixir,exercism/xelixir,victorlcampos/xelixir,tjcelaya/xelixir