Generate WETRecords from filepath.

def wet_records(wet_filepath):
  """Generate WETRecords from filepath."""
  if wet_filepath.endswith('.gz'):
    fopen = gzip.open
  else:
    fopen = tf.gfile.GFile

  with fopen(wet_filepath) as f:
    for record in wet_records_from_file_obj(f):
      yield record