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': {}}
