====== Avoid double negations ======

{{tag>gateway}}

Double negations make business logic confusing.

===== ✔ How to =====

<diagram><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="295px" height="158px" viewBox="-0.5 -0.5 295 158" content="&lt;mxfile host=&quot;embed.diagrams.net&quot; modified=&quot;2024-01-17T18:03:27.522Z&quot; agent=&quot;Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36&quot; etag=&quot;S0s-xZP-VmWCiVsASVke&quot; version=&quot;22.1.21&quot; type=&quot;embed&quot;&gt;&lt;diagram id=&quot;grg7YXjBV2GYVaBwpZ0P&quot; name=&quot;Страница — 1&quot;&gt;1VjbcpswEP0aPzZjwJf40dhJ+pDMZCYPbR9lkEGNYBlJvtCvr4QkQIAzNE3axOMZ0NHqwu7ZI5ZJsMnOdwwV6QPEmE78aXyeBNuJ73v+aiYvCik1cj2dayBhJDZGDfBEfmEDTg16IDHmjqEAoIIULhhBnuNIOBhiDE6u2R6ou2qBEtwDniJE++g3EovUPIW/bPCvmCSpXdlbrHRPhqyxeRKeohhOLSi4mQQbBiD0XXbeYKqcZ/2ix91e6K03xnAuxgzw9YAjogfzbOuiYHDEsv/WbFGU9rkLILmofDcP5X965cu4bexlMpc2mwrXbRdbDtp6Fdgdb2yXQ/N6HcwftnXnlf8glM4u1JNk50Tx8mpXZPlVggQ+oVJ6PkxFRmW3J2+PmAkiA36Pdpg+AieCQC77diAEZNKAqo4QRc8Jg0Meb4ACq5wU7Ktfa441JYkaK6CQKDKtSEYIyyFhgRnJcHW/ZSlkuwN/bKAQDoKSHG9qKk8bULZyUJeQl9kOaNPu88BQQ20Kn1uQ4cUdBrkiK6WJ6Q2mhqOlTVvTPjWUnxsobbHdYsgkWVLP3PBQ3hgqDtNy1qMejmUGmiYwkUICOaI3DRpWcVC81R6qbe5B+b2K6k8sRGnkBB0EuDHHuZUaz9fNtdIKFXUK0bOGbgm19hd9LBBLsHASTG3/RaczTJEgR1dghlxohj6qVGyCVQuKDdZs7k7B4cAibEZ1AlFvY1Rs5p8hNvhMxHe1nJQA3fphFlf323O7UbYarcyrsIsx1v78tzEOOjGej4txb6JZJ7OvOxmr+dubR3oclS0zcxpc3G9gqeIu0zBPT/haHtqXgdbZVWI+SM5KxV1C9WS4q9YZiWPNXczJL7Sr5lOUcA/B7SBJ5hfEtn4lMfM5p/6QCMvjbbFaOG78YmZ6LZusCez3HP+tGCw+rxh4n1oMgq4YdJP4tWJQ59U7q4Fd50/39VbyseqpRw4fQzwWbycewcoLPq54XPdC8D/UZFRWm8ruXd/sxr4cL3tuW3OOOVcFtaSbJODIum100TZQsY0o47zhGm45VMRdLOy8garu5VKvhfkj6j+BuDoxTikR+KlAVcBPsrtK3khY8tU0C7k5eqYujWRuCiRrMlYfLQXKLS0joBQVnDRCoJZ9QOy5skc7LhhS1d1bFG5etxawX1dahVtt067cukfICHLKZvOxQktA88knuPkN&lt;/diagram&gt;&lt;/mxfile&gt;"><defs/><g><path d="M 205 53 L 230 78 L 205 103 L 180 78 Z" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 110px; margin-left: 205px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: #ffffff; " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">Approved?</div></div></div></foreignObject><text x="205" y="122" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">Approved?</text></switch></g><path d="M 100 78 L 135.5 78.5 L 165.88 78.16" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 178.88 78.01 L 165.96 84.66 L 165.81 71.66 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><path d="M 205 53 L 205 13 L 265.88 13" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 278.88 13 L 265.88 19.5 L 265.88 6.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 15px; margin-left: 239px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 11px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">yes</div></div></div></foreignObject><text x="239" y="18" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="11px" text-anchor="middle">yes</text></switch></g><path d="M 205 103 L 205 143 L 265.88 143" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 278.88 143 L 265.88 149.5 L 265.88 136.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 145px; margin-left: 246px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 11px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">no</div></div></div></foreignObject><text x="246" y="148" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="11px" text-anchor="middle">no</text></switch></g><path d="M 120 78 L 173.63 78" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 178.88 78 L 171.88 81.5 L 173.63 78 L 171.88 74.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><path d="M 0 48 C 0 42.48 4.48 38 10 38 L 110 38 C 115.52 38 120 42.48 120 48 L 120 108 C 120 113.52 115.52 118 110 118 L 10 118 C 4.48 118 0 113.52 0 108 L 0 48 Z" fill="rgb(255, 255, 255)" stroke="none" pointer-events="all"/><path d="M 2 49 L 2 107 C 2 111.97 6.03 116 11 116 L 109 116 C 113.97 116 118 111.97 118 107 L 118 49 C 118 44.03 113.97 40 109 40 L 11 40 C 6.03 40 2 44.03 2 49" fill="none" stroke="none" pointer-events="all"/><path d="M 0 48 C 0 42.48 4.48 38 10 38 L 110 38 C 115.52 38 120 42.48 120 48 L 120 108 C 120 113.52 115.52 118 110 118 L 10 118 C 4.48 118 0 113.52 0 108 L 0 48 Z" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 118px; height: 1px; padding-top: 78px; margin-left: 1px;"><div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">Assess design</div></div></div></foreignObject><text x="60" y="82" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">Assess design</text></switch></g></g></svg></diagram>

===== ✘ How NOT to =====

<diagram><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="295px" height="158px" viewBox="-0.5 -0.5 295 158" content="&lt;mxfile host=&quot;embed.diagrams.net&quot; modified=&quot;2024-01-17T18:02:48.965Z&quot; agent=&quot;Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36&quot; etag=&quot;zI_RpG8iipaXd7urMxdU&quot; version=&quot;22.1.21&quot; type=&quot;embed&quot;&gt;&lt;diagram id=&quot;grg7YXjBV2GYVaBwpZ0P&quot; name=&quot;Страница — 1&quot;&gt;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&lt;/diagram&gt;&lt;/mxfile&gt;"><defs/><g><path d="M 205 53 L 230 78 L 205 103 L 180 78 Z" fill="rgb(255, 255, 255)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe flex-start; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 110px; margin-left: 205px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: #ffffff; " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">Rejected?</div></div></div></foreignObject><text x="205" y="122" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">Rejected?</text></switch></g><path d="M 100 78 L 135.5 78.5 L 165.88 78.16" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 178.88 78.01 L 165.96 84.66 L 165.81 71.66 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><path d="M 205 53 L 205 13 L 265.88 13" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 278.88 13 L 265.88 19.5 L 265.88 6.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 15px; margin-left: 239px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 11px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">no</div></div></div></foreignObject><text x="239" y="18" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="11px" text-anchor="middle">no</text></switch></g><path d="M 205 103 L 205 143 L 265.88 143" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 278.88 143 L 265.88 149.5 L 265.88 136.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 1px; height: 1px; padding-top: 145px; margin-left: 246px;"><div data-drawio-colors="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 11px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; background-color: rgb(255, 255, 255); white-space: nowrap;">yes</div></div></div></foreignObject><text x="246" y="148" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="11px" text-anchor="middle">yes</text></switch></g><path d="M 120 78 L 173.63 78" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="stroke"/><path d="M 178.88 78 L 171.88 81.5 L 173.63 78 L 171.88 74.5 Z" fill="rgb(0, 0, 0)" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><path d="M 0 48 C 0 42.48 4.48 38 10 38 L 110 38 C 115.52 38 120 42.48 120 48 L 120 108 C 120 113.52 115.52 118 110 118 L 10 118 C 4.48 118 0 113.52 0 108 L 0 48 Z" fill="rgb(255, 255, 255)" stroke="none" pointer-events="all"/><path d="M 2 49 L 2 107 C 2 111.97 6.03 116 11 116 L 109 116 C 113.97 116 118 111.97 118 107 L 118 49 C 118 44.03 113.97 40 109 40 L 11 40 C 6.03 40 2 44.03 2 49" fill="none" stroke="none" pointer-events="all"/><path d="M 0 48 C 0 42.48 4.48 38 10 38 L 110 38 C 115.52 38 120 42.48 120 48 L 120 108 C 120 113.52 115.52 118 110 118 L 10 118 C 4.48 118 0 113.52 0 108 L 0 48 Z" fill="none" stroke="rgb(0, 0, 0)" stroke-miterlimit="10" pointer-events="all"/><g transform="translate(-0.5 -0.5)"><switch><foreignObject pointer-events="none" width="100%" height="100%" requiredFeatures="http://www.w3.org/TR/SVG11/feature#Extensibility" style="overflow: visible; text-align: left;"><div xmlns="http://www.w3.org/1999/xhtml" style="display: flex; align-items: unsafe center; justify-content: unsafe center; width: 118px; height: 1px; padding-top: 78px; margin-left: 1px;"><div data-drawio-colors="color: rgb(0, 0, 0); " style="box-sizing: border-box; font-size: 0px; text-align: center;"><div style="display: inline-block; font-size: 12px; font-family: Helvetica; color: rgb(0, 0, 0); line-height: 1.2; pointer-events: all; white-space: normal; overflow-wrap: normal;">Assess design</div></div></div></foreignObject><text x="60" y="82" fill="rgb(0, 0, 0)" font-family="Helvetica" font-size="12px" text-anchor="middle">Assess design</text></switch></g></g></svg></diagram>

===== Author(s) =====

 --- //[[user:bell|Anatoly Belaychuk]] 2024-01-17 20:59//