public function setLeftnode($leftnode)
    {
        if (false === Numeric::isPositiveInteger($leftnode)) {
            throw new InvalidArgumentException('A nested node position must be a strictly positive integer.');
        }

        $this->_leftnode = $leftnode;

        return $this;
    }
public function setLeftnode($leftnode)
    {
        if (false === Numeric::isPositiveInteger($leftnode)) {
            throw new InvalidArgumentException('A nested node position must be a strictly positive integer.');
        }

        $this->_leftnode = $leftnode;

        return $this;
    }
public function setLeftnode ( $ leftnode ) { if ( false === Numeric :: isPositiveInteger ( $ leftnode ) ) { throw new InvalidArgumentException ( 'A nested node position must be a strictly positive integer.' ) ; } $ this -> _leftnode = $ leftnode ; return $ this ; }
Sets the left position.
@param  int                                         $leftnode
@return \BackBee\NestedNode\AbstractNestedNode
@throws \BackBee\Exception\InvalidArgumentException Occurs if the value can not be cast to positive integer
Sets the left position .