code: public function isRegisteredAlias(Model $objModel, $strAlias, $varValue)
  	{
  		$strTable = $objModel->getTable();
  
  		return isset($this->arrAliases[$strTable][$strAlias][$varValue]);
  	}
docs: Check if an alias is registered
  
  @param Model  $objModel The model object
  @param string $strAlias The alias name
  @param mixed  $varValue The value of the alias
  
  @return boolean True if the alias is registered