def lines_in_all(files,
                 lines):
  """Enumerate lines in multiple files.

  Args:
    files: If specified, a file-like or array of file-like objects.
    lines: If specified, an array of strings.

  Yields:
    a string for each line in each file or string.
  """
  if files:
    file_set = files if isinstance(files, list) else [files]
    for one_file in file_set:
      for line in lines_in(one_file):
        yield line
  if lines:
    for line in lines_in(lines):
      yield line
Enumerate lines in multiple files.

  Args:
    files: If specified, a file-like or array of file-like objects.
    lines: If specified, an array of strings.

  Yields:
    a string for each line in each file or string.
  
language/nql/nql/io.py