def find_indentation(about_page_lines):
    """Finds indentation used for span and li elements to list developer
    names in about-page.component.html.

    Args:
        about_page_lines: list(str). List of lines in
            about-page.component.html.

    Returns:
        tuple(str, str). A tuple of span indent and li indent.
    """

    span_text = '<span>A</span>'

    span_line = ''
    li_line = ''
    for index, line in enumerate(about_page_lines):
        if line.find(span_text) != -1:
            span_line = line
            if index + 2 < len(about_page_lines):
                li_line = about_page_lines[index + 2]
            break
    if not span_line:
        raise Exception(
            'Expected about-page.component.html to have %s.' % span_text)
    span_indent = span_line[:span_line.find(span_text)]

    if li_line.find('<li>') == -1:
        # The format should be:
        # <span>A</span>
        #   <ul>
        #     <li>A*</li>.
        raise Exception(
            'Expected %s text to be followed by an unordered list in '
            'about-page.component.html' % span_text)
    li_indent = li_line[:li_line.find('<li>')]
    return (span_indent, li_indent)