sigil binary package in Ubuntu Focal amd64

 Sigil is a free, open source, multi-platform ebook editor.
 It is designed to edit books in ePub format.
 .
 Features:
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  * Full UTF-16 support;
  * Full EPUB 2 spec support;
  * Multiple Views: Book View, Code View and Preview View;
  * WYSIWYG editing in Book View;
  * Complete control over directly editing EPUB syntax in Code View;
  * Table of Contents generator with multi-level heading support;
  * Metadata editor with full support for all possible metadata entries (more
    than 200) with full descriptions for each;
  * User interface translated into many languages;
  * Spell checking with default and user configurable dictionaries;
  * Full Regular Expression (PCRE) support for Find & Replace;
  * Supports import of EPUB and HTML files, images, and style sheets;
  * Files can be validated for EPUB compliance with the FlightCrew validator;
  * HTML Tidy: all imported files have their formatting corrected, and your
    editing can be optionally cleaned.

Source package