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#!/usr/bin/python2.5

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import werkzeug

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from werkzeug.exceptions import HTTPException

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import wsgiref.handlers

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from PIL import Image, ImageDraw, ImageFont, ImageEnhance

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from cStringIO import StringIO

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import random, itertools

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if not hasattr(itertools, 'izip_longest') :

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    def izip_longest(*args, **kwds):

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        # izip_longest('ABCD', 'xy', fillvalue='-') --> Ax By C- D-

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        fillvalue = kwds.get('fillvalue')

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        def sentinel(counter = ([fillvalue]*(len(args)-1)).pop):

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            yield counter()         # yields the fillvalue, or raises IndexError

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        fillers = itertools.repeat(fillvalue)

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        iters = [itertools.chain(it, sentinel(), fillers) for it in args]

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        try:

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            for tup in itertools.izip(*iters):

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                yield tup

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        except IndexError:

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            pass

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    itertools.izip_longest = izip_longest 

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class Defaults :

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    # settings

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    text = [

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        "aalto",

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        "unive",

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        "rsity"

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    ]

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    chars = [ '"', '!', '?' ]

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    line_colors = [

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        "#0469af",

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        "#fbc614",

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        "#e1313b",

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    ]

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    font_name = 'helvetica'

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    font_size = 30

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    background_color = "#ffffff"

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    line_spacing = -10

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    sharpness = 0.6

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fonts = {

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        'dejavu-sans-bold':     "/usr/share/fonts/truetype/ttf-dejavu/DejaVuSans-Bold.ttf",

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        'helvetica':            "HELR65W.TTF",

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    }

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# enable debugging

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def randomize (seq) :

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    """

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        Returns the given sequence in random order as a list

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    """

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    # copy

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    l = list(seq)

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    # rearrange

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    random.shuffle(l)

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    return l

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def build_data (text, chars, line_colors) :

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    """

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        Returns a matrix of (text, color) tuples representing the data to render

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        [ [ (str, str) ] ]

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            text        - list of lines

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            chars       - list of random chars to interpse

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            line_colors - list of colors to draw the chars in

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    """

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    data = []

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    for line, char, color in itertools.izip_longest(text, chars, line_colors, fillvalue=None) :

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        # pick position to place char

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        pos = random.randint(1, len(line) - 1)

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        if not color :

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            color = "#000000"

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        # split into three parts

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        if char :

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            data.append([

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                    (line[:pos], "#000000"),

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                    (char, color),

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                    (line[pos:], "#000000"),

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                ])

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        else :

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            data.append([

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                    (line, "#000000"),

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                ])

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    return data

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def load_font (font_name, font_size) :

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    """

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        Load a font by name

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    """

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    # load font

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    font_path = fonts[font_name]

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    font = ImageFont.truetype(font_path, font_size)

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    return font

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def render_img (data, font, background_color="#ffffff", line_spacing=0) :

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    """

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        Render the data (as from build_data) as an image, using the given PIL.ImageFont, and return the PIL Image object

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    """

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    img_width = img_height = 0

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    img_data = []

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    # compute image width/height

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    for segments in data :

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        line_width = line_height = 0

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        # build a new list of segments with additional info

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        line_segments = []

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        for seg_text, seg_color in segments :

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            # compute rendered text size

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            seg_width, seg_height = font.getsize(seg_text)

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            # update line_*

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            line_width += seg_width

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            line_height = max(line_height, seg_height)

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            # build the new segments list

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            line_segments.append((seg_text, seg_color, seg_width))

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        # update img_*

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        img_width = max(img_width, line_width)

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        img_height += line_height

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        img_data.append((line_segments, line_height))

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    # calculate height needed for line spacing

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    img_height += (len(img_data) - 1) * line_spacing

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    # create image

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    img = Image.new("RGB", (img_width, img_height), background_color)

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    draw = ImageDraw.Draw(img)

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    # draw text

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    img_y = 0

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    for segments, line_height in img_data :

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        img_x = 0

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        # draw each segment build above, incremeing along img_x

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        for seg_text, seg_color, seg_width in segments :

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            draw.text((img_x, img_y), seg_text, font=font, fill=seg_color)

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            img_x += seg_width

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        img_y += line_height + line_spacing

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    return img

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def effect_sharpness (img, factor) :

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    """

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        Sharpen the image by the given factor

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    """

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    return ImageEnhance.Sharpness(img).enhance(factor)

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def build_png (img) :

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    """

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        Write the given PIL.Image as a string, returning the raw binary data

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    """

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    # render PNG output

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    buf = StringIO()

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    img.save(buf, "png")

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    data = buf.getvalue()

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    return data

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def arg_bool (val) :

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    if val.lower() in ('true', 't', '1', 'yes', 'y') :

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        return True

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    elif val.lower() in ('false', 'f', '0', 'no', 'n') :

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        return False

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    else :

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        raise ValueError(val)

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def arg_color (val) :

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    if val.beginswith('#') :

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        int(val[1:], 16)

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        return val

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    else :

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        raise ValueError(val)

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def handle_request (req) :

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    # parse args

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    if 'text' in req.args :

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        text = req.args.getlist('text', unicode)

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    else :

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        text = Defaults.text

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    if 'chars' in req.args :

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        chars = req.args.getlist('chars', unicode)

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    else :

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        chars = Defaults.chars

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    if 'colors' in req.args :

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        colors = req.args.getlist('colors', arg_color)

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    else :

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        colors = Defaults.line_colors

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    font_name = req.args.get('font', Defaults.font_name)

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    font_size = req.args.get('font-size', Defaults.font_size, int)

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    background_color = req.args.get('background-color', Defaults.background_color, arg_color)

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    line_spacing = req.args.get('line-spacing', Defaults.line_spacing, int)

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    sharpness = req.args.get('sharpness', Defaults.sharpness, float)

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    # put the chars in random order by default

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    if req.args.get('random-chars', True, arg_bool) :

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        chars = randomize(chars)

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    # load/prep resources

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    data = build_data(text, chars, colors)

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    font = load_font(font_name, font_size)

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    # render the image

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    img = render_img(data, font, background_color, line_spacing)

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    img = effect_sharpness(img, sharpness)

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    png_data = build_png(img)

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    # build the response

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    response = werkzeug.Response(png_data, mimetype='image/png')

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    return response

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@werkzeug.Request.application

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def wsgi_application (request) :

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    """

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        Our werkzeug WSGI handler

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    """

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    try :

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        # request -> response

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        response = handle_request(request)

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        return response

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    except HTTPException, e :

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        # return as HTTP response

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        return e

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def main () :

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    handler = wsgiref.handlers.CGIHandler()

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    app = wsgi_application

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        # enable debugging

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        app = werkzeug.DebuggedApplication(app, evalex=False)

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    handler.run(app)

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if __name__ == '__main__' :

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    main()

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