title: Get file size stored (GCP) in a bucket with airflow
body: <p>The context is that I need to end the process if a file, stored in Google Cloud Platform is empty, but if isn´t empty, follow the normal workflow. I´m doing this with a branch operator in airflow, but i have to pass a condition to decide if the process needs to end there, or continue.</p>
  <p>So my question is: how can I get the size of a flat file stored in a bucket in GCP?</p>
  <p>Thanks in advance!</p>