code: public function attr($attrKey, $attrValue = null) {
  			if ( !is_null($attrValue) ) {
  				if ( !is_array($this->attributes) ) {
  					$this->attributes = array();
  				}
  				$this->attributes[$attrKey] = $attrValue;
  				return $this;
  			} else {
  				if ( array_key_exists($attrKey, $this->attributes) ) {
  					return $this->attributes[$attrKey];
  				} else {
  					return null;
  				}
  			}
  			
  		}
docs: Set's an attribute for the current element
  
  @param  mixed 	 $attrKey		The name of the attribute
  @param  string    $attrValue		The value of the attribute
  
  @return mixed 					Could be an \SVGCreator\Element or could be the value of the attribute,
  this means that the second parameter wasn't passed