src/main/php/Invocations.php
public function argumentName(int $argumentPosition, string $suffix = ''): ?string
    {
        if  (isset($this->paramNames[$argumentPosition])) {
            return '$' . $this->paramNames[$argumentPosition] . $suffix;
        }

        return null;
    }
public function argumentName(int $argumentPosition, string $suffix = ''): ?string
    {
        if  (isset($this->paramNames[$argumentPosition])) {
            return '$' . $this->paramNames[$argumentPosition] . $suffix;
        }

        return null;
    }
public function argumentName ( int $ argumentPosition , string $ suffix = '' ) : ? string { if ( isset ( $ this -> paramNames [ $ argumentPosition ] ) ) { return '$' . $ this -> paramNames [ $ argumentPosition ] . $ suffix ; } return null ; }
returns name of argument at requested position

Returns null if there is no argument at requested position or the name
of that argument is unknown.

@param   int     $argumentPosition
@param   string  $suffix            optional  string to append after argument name
@return  string|null
returns name of argument at requested position