To get a file that was uploaded via a File Field in the previous step:
records = seal.get_previous_step_records()
# the previous step has a record with a file field named "File"
fie_id = records[0]['fields']['File']['value']
# download the file to the VM's temp filesystem
file_path = seal.download_file(file_id)
# load that file into a pandas dataframe
df = pd.read_csv(file_path)
