presto-spi/src/main/java/io/prestosql/spi/transaction/IsolationLevel.java/IsolationLevel/meetsRequirementOf
class IsolationLevel:    public boolean meetsRequirementOf(IsolationLevel requirement)
    {
        switch (this) {
            case READ_UNCOMMITTED:
                return requirement == READ_UNCOMMITTED;

            case READ_COMMITTED:
                return requirement == READ_UNCOMMITTED ||
                        requirement == READ_COMMITTED;

            case REPEATABLE_READ:
                return requirement == READ_UNCOMMITTED ||
                        requirement == READ_COMMITTED ||
                        requirement == REPEATABLE_READ;

            case SERIALIZABLE:
                return true;
        }

        throw new AssertionError("Unhandled isolation level: " + this);
    }