def main(argv=None):
    """
    Main entry method for AnchorHub. Takes in command-line arguments,
    finds files to parse within the specified input directory, and outputs
    parsed files to the specified output directory.

    :param argv: a list of string command line arguments
    """
    # Get command line arguments, validate them, and normalize them
    opts = cmdparse.parse_args(argv)
    assert validate_opts.validate(opts)
    opts = normalize_opts.normalize(opts)

    if opts.verbose:
        # Update client: print input and output directories
        messages.print_input_output(opts)

    file_paths = fileparse.get_file_list(opts)
    assert validate_files.validate(file_paths, opts)

    if opts.verbose and opts.is_dir:
        # Update client: print files that will be parsed
        messages.print_files(opts, file_paths)

    # For now, only using default GitHub Markdown for parsing
    # Collect tag/anchor combinations
    collector = make_github_markdown_collector(opts)
    anchors, duplicate_tags = collector.collect(file_paths)
    assert validate_anchors.validate(anchors, duplicate_tags, opts)

    # Write files using previously found AnchorHub tags and generated anchors
    writer = make_github_markdown_writer(opts)
    counter = writer.write(file_paths, anchors, opts)

    if opts.verbose:
        if opts.is_dir:
            # Update client: print files that had modifications
            messages.print_modified_files(opts, anchors)
        # Print summary statistics
        messages.print_summary_stats(counter)
Main entry method for AnchorHub. Takes in command-line arguments,
    finds files to parse within the specified input directory, and outputs
    parsed files to the specified output directory.

    :param argv: a list of string command line arguments