Emitted when --find-dead-code is turned on and Psalm cannot find any uses of a particular parameter in a private method or function
<?php
function foo(int $a, int $b) : int {
return $a + 4;
}Can be suppressed by prefixing the parameter name with an underscore:
function foo(int $_a, int $b) : int {
return $b + 4;
}