def _null_cast(dic, key):
    """
    Allows the user to load value, given key from the dictionary. If the key
    is not found, return "null".
    
    Args:
        dic (dict): Dictionary in look for (key, value) pair
        key (str): Key to look search in the dictionary
        
    Returns:
        type: str
        Either "null" string or previous data stored in the field.
    
    """
    if key not in dic:
        return "null"
    return dic[key]