What is Null Coalesce Operator which is newly introduced in php 7 ?
// ?? operator $name = $firstName ?? "Guest";
if the value is set to not null or if value exist in the left it will return the left side value ($firstname),
if the value is null and not defined in left it will return the right side value ("Guest"),
Note: it will not through notice if $firstName variable is not defined or non-existent.
And you know what it is equivalent to