docs: def concatenate(input_files, output_file):
      """
      Concatenates the input files into the single output file.
  
      In debug mode this function adds a comment with the filename
      before the contents of each file.
      """
      from .modules import utils, concat
  
      if not isinstance(input_files, (list, tuple)):
          raise RuntimeError('Concatenate takes a list of input files.')
  
      return {
          'dependencies_fn': utils.no_dependencies,
          'compiler_fn': concat.concatenate_input_files,
          'input': input_files,
          'output': output_file,
          'kwargs': {},
      }