PHP : PHP: Check if variable exist but also if has a value equal to something

PHP : PHP: Check if variable exist but also if has a value equal to something
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

So here is a secret hidden feature I promissed to tell you.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
Then, type the letters 'awesome' on the keyboard.
Your YouTube progress indicator will turn into a shimmering rainbow.

A quick introduction about me,
Hi, my name is Delphi, nice to meet you.
I am willing to help you find the solutions to your questions.
PHP : PHP: Check if variable exist but also if has a value equal to something
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Your input is appreciated, so please leave a comment below with your answer or insights to the answer.
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Check to something equal : if has if PHP: value a PHP exist but variable also