def check_conditions(directory, conditions):
    """
    Function to check if a condition is known and accounted for.
    
    Parameters
    ----------
    directory : string
        the name of a directory that is the condition to check for
        
    conditions : list of strings
        a list of known and accounted for conditions
        
    Returns
    -------
    directory : string or None
        either returns an unaccounted-for condition or returns None.
    """
    for condition in conditions:
        if condition in directory:
            return None
    return directory