src/Datastructure/Stackqueue/Queue.php
public function front() {
        if (null === $this->queue) return null;
        if ($this->tail > $this->head) return null;
        return $this->queue[$this->tail];
    }
public function front() {
        if (null === $this->queue) return null;
        if ($this->tail > $this->head) return null;
        return $this->queue[$this->tail];
    }
public function front ( ) { if ( null === $ this -> queue ) return null ; if ( $ this -> tail > $ this -> head ) return null ; return $ this -> queue [ $ this -> tail ] ; }
returns the first element from the queue

@return int
returns the first element from the queue