def symbol_type(symbol):
    """Determines the type of the asset the symbol represents.
    This can be 'STOCK', 'CRYPTO', or 'OPTION'
    """
    if len(symbol) > 6:
        return "OPTION"
    elif symbol[0] == "@" or symbol[:2] == "c_":
        return "CRYPTO"
    else:
        return "STOCK"