Translate the following question to SQL: Return the total revenue of companies with headquarters in Tokyo or Taiwan.

Schema: CREATE TABLE Manufacturers (
    Code INTEGER   PRIMARY KEY,
    Name VARCHAR(255) NOT NULL,
    Headquarter VARCHAR(255) NOT NULL,
    Founder VARCHAR(255) NOT NULL,
    Revenue REAL
);

CREATE TABLE Products (
    Code INTEGER   PRIMARY KEY,
    Name VARCHAR(255) NOT NULL,
    Price DECIMAL NOT NULL,
    Manufacturer INTEGER NOT NULL,
    FOREIGN KEY (Manufacturer) REFERENCES Manufacturers(Code)
);
user
SELECT sum(revenue) FROM manufacturers WHERE Headquarter  =  'Tokyo' OR Headquarter  =  'Taiwan'
assistant