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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 tweak_css(repo_dir):
    '''Comment out some css settings.'''
    print_msg("* don't capitalize titles (no uppercase headings)")
    files = [
        'beige.css', 'black.css', 'blood.css', 'league.css', 'moon.css',
        'night.css', 'serif.css', 'simple.css', 'sky.css', 'solarized.css',
        'white.css',
    ]
    line = '  text-transform: uppercase;'
    for file_ in files:
        update_or_append_line(filename=flo('{repo_dir}/css/theme/{file_}'),
                              prefix=line, new_line=flo('/*{line}*/'))

    print_msg('* images without border')
    data = [
        {'file': 'beige.css',     'line': '  border: 4px solid #333;'},
        {'file': 'black.css',     'line': '  border: 4px solid #fff;'},
        {'file': 'blood.css',     'line': '  border: 4px solid #eee;'},
        {'file': 'league.css',    'line': '  border: 4px solid #eee;'},
        {'file': 'moon.css',      'line': '  border: 4px solid #93a1a1;'},
        {'file': 'night.css',     'line': '  border: 4px solid #eee;'},
        {'file': 'serif.css',     'line': '  border: 4px solid #000;'},
        {'file': 'simple.css',    'line': '  border: 4px solid #000;'},
        {'file': 'sky.css',       'line': '  border: 4px solid #333;'},
        {'file': 'solarized.css', 'line': '  border: 4px solid #657b83;'},
        {'file': 'white.css',     'line': '  border: 4px solid #222;'},
    ]
    for item in data:
        file_ = item['file']
        lines = [item['line'], ]
        lines.extend(['  box-shadow: 0 0 10px rgba(0, 0, 0, 0.15); }',
                      '  box-shadow: 0 0 20px rgba(0, 0, 0, 0.55); }'])
        for line in lines:
            update_or_append_line(filename=flo('{repo_dir}/css/theme/{file_}'),
                                  prefix=line, new_line=flo('/*{line}*/'))