#!/usr/bin/env python

# Import the Arvados sdk module
import arvados

# Get information about the task from the environment
this_task = arvados.current_task()

this_task_input = arvados.current_job()['script_parameters']['input']

# Create the object access to the collection referred to in the input
collection = arvados.CollectionReader(this_task_input)

# Create an object to write a new collection as output
out = arvados.CollectionWriter()

# Create a new file in the output collection
with out.open('0-filter.txt') as out_file:
    # Iterate over every input file in the input collection
    for input_file in collection.all_files():
        # Output every line in the file that starts with '0'
        out_file.writelines(line for line in input_file if line.startswith('0'))

# Commit the output to keep.  This returns a Keep id.
output_id = out.finish()

# Set the output for this task to the Keep id
this_task.set_output(output_id)

# Done!