new_contents: #!/usr/bin/env python2
  
  import argparse
  import yaml
  import sys
  
  parser = argparse.ArgumentParser(description='Extract values for a single key from a yaml sequence of mappings')
  parser.add_argument('key', help='Extract values for this key.')
  args = parser.parse_args()
  
  # Load YAML from standard in
  data = yaml.safe_load(sys.stdin)
  
  # List comprehension to extract value by key
  values = [d[args.key] for d in data if args.key in d]
  
  # Print values
  for v in values:
      print(v)
  
subject: Add yamlcol.py