termux-app

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package com.termux.shared.markdown;
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import android.content.Context;
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import android.graphics.Typeface;
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import android.text.Spanned;
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import android.text.style.AbsoluteSizeSpan;
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import android.text.style.BackgroundColorSpan;
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import android.text.style.BulletSpan;
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import android.text.style.QuoteSpan;
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import android.text.style.StrikethroughSpan;
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import android.text.style.StyleSpan;
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import android.text.style.TypefaceSpan;
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import android.text.util.Linkify;
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import androidx.annotation.NonNull;
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import androidx.core.content.ContextCompat;
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import com.google.common.base.Strings;
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import com.termux.shared.R;
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import com.termux.shared.theme.ThemeUtils;
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import org.commonmark.ext.gfm.strikethrough.Strikethrough;
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import org.commonmark.node.BlockQuote;
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import org.commonmark.node.Code;
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import org.commonmark.node.Emphasis;
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import org.commonmark.node.FencedCodeBlock;
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import org.commonmark.node.ListItem;
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import org.commonmark.node.StrongEmphasis;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import io.noties.markwon.AbstractMarkwonPlugin;
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import io.noties.markwon.Markwon;
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import io.noties.markwon.MarkwonSpansFactory;
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import io.noties.markwon.MarkwonVisitor;
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import io.noties.markwon.ext.strikethrough.StrikethroughPlugin;
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import io.noties.markwon.linkify.LinkifyPlugin;
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public class MarkdownUtils {
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    public static final String backtick = "`";
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    public static final Pattern backticksPattern = Pattern.compile("(" + backtick + "+)");
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    /**
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     * Get the markdown code {@link String} for a {@link String}. This ensures all backticks "`" are
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     * properly escaped so that markdown does not break.
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     *
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     * @param string The {@link String} to convert.
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     * @param codeBlock If the {@link String} is to be converted to a code block or inline code.
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     * @return Returns the markdown code {@link String}.
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     */
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    public static String getMarkdownCodeForString(String string, boolean codeBlock) {
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        if (string == null) return null;
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        if (string.isEmpty()) return "";
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        int maxConsecutiveBackTicksCount = getMaxConsecutiveBackTicksCount(string);
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        // markdown requires surrounding backticks count to be at least one more than the count
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        // of consecutive ticks in the string itself
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        int backticksCountToUse;
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        if (codeBlock)
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            backticksCountToUse = maxConsecutiveBackTicksCount + 3;
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        else
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            backticksCountToUse = maxConsecutiveBackTicksCount + 1;
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        // create a string with n backticks where n==backticksCountToUse
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        String backticksToUse = Strings.repeat(backtick, backticksCountToUse);
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        if (codeBlock)
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            return backticksToUse + "\n" + string + "\n" + backticksToUse;
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        else {
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            // add a space to any prefixed or suffixed backtick characters
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            if (string.startsWith(backtick))
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                string = " " + string;
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            if (string.endsWith(backtick))
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                string = string + " ";
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            return backticksToUse + string + backticksToUse;
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        }
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    }
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    /**
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     * Get the max consecutive backticks "`" in a {@link String}.
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     *
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     * @param string The {@link String} to check.
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     * @return Returns the max consecutive backticks count.
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     */
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    public static int getMaxConsecutiveBackTicksCount(String string) {
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        if (string == null || string.isEmpty()) return 0;
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        int maxCount = 0;
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        int matchCount;
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        String match;
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        Matcher matcher = backticksPattern.matcher(string);
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        while(matcher.find()) {
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            match = matcher.group(1);
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            matchCount = match != null ? match.length() : 0;
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            if (matchCount > maxCount)
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                maxCount = matchCount;
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        }
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        return maxCount;
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    }
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    public static String getLiteralSingleLineMarkdownStringEntry(String label, Object object, String def) {
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        return "**" + label + "**: " + (object != null ? object.toString() : def) +  "  ";
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    }
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    public static String getSingleLineMarkdownStringEntry(String label, Object object, String def) {
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        if (object != null)
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            return "**" + label + "**: " + getMarkdownCodeForString(object.toString(), false) +  "  ";
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        else
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            return "**" + label + "**: " + def +  "  ";
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    }
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    public static String getMultiLineMarkdownStringEntry(String label, Object object, String def) {
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        if (object != null)
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            return "**" + label + "**:\n" + getMarkdownCodeForString(object.toString(), true) + "\n";
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        else
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            return "**" + label + "**: " + def + "\n";
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    }
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    public static String getLinkMarkdownString(String label, String url) {
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        if (url != null)
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            return "[" + label.replaceAll("]", "\\\\]") + "](" + url.replaceAll("\\)", "\\\\)") +  ")";
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        else
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            return label;
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    }
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    /** Check following for more info:
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     * https://github.com/noties/Markwon/tree/v4.6.2/app-sample
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     * https://noties.io/Markwon/docs/v4/recycler/
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     * https://github.com/noties/Markwon/blob/v4.6.2/app-sample/src/main/java/io/noties/markwon/app/readme/ReadMeActivity.kt
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     */
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    public static Markwon getRecyclerMarkwonBuilder(Context context) {
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        return Markwon.builder(context)
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            .usePlugin(LinkifyPlugin.create(Linkify.EMAIL_ADDRESSES | Linkify.WEB_URLS))
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            .usePlugin(new AbstractMarkwonPlugin() {
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                @Override
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                public void configureVisitor(@NonNull MarkwonVisitor.Builder builder) {
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                    builder.on(FencedCodeBlock.class, (visitor, fencedCodeBlock) -> {
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                        // we actually won't be applying code spans here, as our custom xml view will
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                        // draw background and apply mono typeface
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                        //
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                        // NB the `trim` operation on literal (as code will have a new line at the end)
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                        final CharSequence code = visitor.configuration()
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                            .syntaxHighlight()
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                            .highlight(fencedCodeBlock.getInfo(), fencedCodeBlock.getLiteral().trim());
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                        visitor.builder().append(code);
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                    });
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                }
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                @Override
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                public void configureSpansFactory(@NonNull MarkwonSpansFactory.Builder builder) {
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                    // Do not change color for night themes
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                    if (!ThemeUtils.isNightModeEnabled(context)) {
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                        builder
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                            // set color for inline code
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                            .setFactory(Code.class, (configuration, props) -> new Object[]{
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                                new BackgroundColorSpan(ContextCompat.getColor(context, R.color.background_markdown_code_inline)),
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                            });
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                    }
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                }
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            })
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            .build();
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    }
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    /** Check following for more info:
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     * https://github.com/noties/Markwon/tree/v4.6.2/app-sample
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     * https://github.com/noties/Markwon/blob/v4.6.2/app-sample/src/main/java/io/noties/markwon/app/samples/notification/NotificationSample.java
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     */
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    public static Markwon getSpannedMarkwonBuilder(Context context) {
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        return Markwon.builder(context)
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                .usePlugin(StrikethroughPlugin.create())
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                .usePlugin(new AbstractMarkwonPlugin() {
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                    @Override
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                    public void configureSpansFactory(@NonNull MarkwonSpansFactory.Builder builder) {
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                        builder
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                            .setFactory(Emphasis.class, (configuration, props) -> new StyleSpan(Typeface.ITALIC))
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                            .setFactory(StrongEmphasis.class, (configuration, props) -> new StyleSpan(Typeface.BOLD))
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                            .setFactory(BlockQuote.class, (configuration, props) -> new QuoteSpan())
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                            .setFactory(Strikethrough.class, (configuration, props) -> new StrikethroughSpan())
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                            // NB! notification does not handle background color
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                            .setFactory(Code.class, (configuration, props) -> new Object[]{
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                                new BackgroundColorSpan(ContextCompat.getColor(context, R.color.background_markdown_code_inline)),
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                                new TypefaceSpan("monospace"),
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                                new AbsoluteSizeSpan(48)
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                            })
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                            // NB! both ordered and bullet list items
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                            .setFactory(ListItem.class, (configuration, props) -> new BulletSpan());
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                    }
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                })
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                .build();
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    }
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    public static Spanned getSpannedMarkdownText(Context context, String string) {
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        if (context == null || string == null) return null;
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        final Markwon markwon = getSpannedMarkwonBuilder(context);
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        return markwon.toMarkdown(string);
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    }
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}
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