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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 html_to_dom(html, default_encoding=DEFAULT_ENCODING, encoding=None, errors=DEFAULT_ENC_ERRORS):
 """Converts HTML to DOM."""

    if isinstance(html, unicode):
        decoded_html = html
        # encode HTML for case it's XML with encoding declaration
        forced_encoding = encoding if encoding else default_encoding
        html = html.encode(forced_encoding, errors)
    else:
        decoded_html = decode_html(html, default_encoding, encoding, errors)

    try:
        dom = lxml.html.fromstring(decoded_html, parser=lxml.html.HTMLParser())
    except ValueError:
        # Unicode strings with encoding declaration are not supported.
        # for XHTML files with encoding declaration, use the declared encoding
        dom = lxml.html.fromstring(html, parser=lxml.html.HTMLParser())

    return dom