code: public function setAvatarSize($size)
  	{
  		// Wipe out the param cache.
  		$this->param_cache = NULL;
  
  		if(!is_int($size) && !ctype_digit($size))
  		{
  			throw new InvalidArgumentException('Avatar size specified must be an integer');
  		}
  
  		$this->size = (int) $size;
  
  		if($this->size > 512 || $this->size < 0)
  		{
  			throw new InvalidArgumentException('Avatar size must be within 0 pixels and 512 pixels');
  		}
  
  		return $this;
  	}
docs: Set the avatar size to use.
  @param integer $size - The avatar size to use, must be less than 512 and greater than 0.
  @return \thomaswelton\GravatarLib\Gravatar - Provides a fluent interface.
  
  @throws \InvalidArgumentException