booleans are used to represent the concepts of true and false. they are most often used for testing if a statement is true or false and they'll play a bigger role when we discuss logical expressions.note that there is a difference between boolean true/false and the strings true/false. booleans and null $bool1:
$bool2:
$var1 is set:
$var2 is set:
$var3 is set:
$var1 is set:
$var2 is set:
$var3 is set:
$var1 empty:
$var4 empty:
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