!checkfileexists does not exist in the current context SQLite - c#

I've been using SQLite for an application that I was writing and when I created a class, everytime I used !checkfileexists, it was always incorrect. Am I missing a using namespace or a reference? Here's the code:

public async Task<bool> onCreate(string databasePath)
{
    try
    {
        if (!CheckFileExists(databasePath).Result)
        {
            using (databaseConnection = new SQLiteConnection(databasePath))
            {

            }
        }
    }
}