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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def markdown_toclify(input_file, output_file=None, github=False, back_to_top=False, nolink=False, no_toc_header=False, spacer=0, placeholder=None, exclude_h=None, remove_dashes=False):
 """ Function to add table of contents to markdown files. Parameters input_file: str Path to the markdown input file. output_file: str (defaul: None) Path to the markdown output file. github: bool (default: False) Uses GitHub TOC syntax if True. back_to_top: bool (default: False) Inserts back-to-top links below headings if True. nolink: bool (default: False) Creates the table of contents without internal links if True. no_toc_header: bool (default: False) Suppresses the Table of Contents header if True spacer: int (default: 0) Inserts horizontal space (in pixels) after the table of contents. placeholder: str (default: None) Inserts the TOC at the placeholder string instead of inserting the TOC at the top of the document. exclude_h: list (default None) Excludes header levels, e.g., if [2, 3], ignores header levels 2 and 3 in the TOC. remove_dashes: bool (default: False) Removes dashes from headline slugs Returns cont: str Markdown contents including the TOC. """

    raw_contents = read_lines(input_file)
    cleaned_contents = remove_lines(raw_contents, remove=('[[back to top]', '<a class="mk-toclify"'))
    processed_contents, raw_headlines = tag_and_collect(
                                            cleaned_contents,
                                            id_tag=not github,
                                            back_links=back_to_top,
                                            exclude_h=exclude_h,
                                            remove_dashes=remove_dashes
                                            )

    leftjustified_headlines = positioning_headlines(raw_headlines)
    processed_headlines = create_toc(leftjustified_headlines,
                                     hyperlink=not nolink,
                                     top_link=not nolink and not github,
                                     no_toc_header=no_toc_header)

    if nolink:
        processed_contents = cleaned_contents

    cont = build_markdown(toc_headlines=processed_headlines,
                          body=processed_contents,
                          spacer=spacer,
                          placeholder=placeholder)

    if output_file:
        output_markdown(cont, output_file)
    return cont