add license to new file, resolving jenkins build issues

[rahul003]

This PR #6549 added a new file which didn't have a header. This caused all builds to fail sanity check.

Example of a build is here

Excerpt from that

Traceback (most recent call last):
  File "tools/license_header.py", line 160, in <module>
    process_folder(os.path.join(os.path.dirname(__file__), '..'), args.action[0])
  File "tools/license_header.py", line 150, in process_folder
    'them automatically', excepts)
Exception: ('The following files do not contain a valid license, you can use `python tools/license_header.py add` to addthem automatically', ['example/bi-lstm-sort/gen_data.py'])

Used this tool to add a header