public String readAsciiString() throws IOException {
        return readString(readVarInt(), StandardCharsets.US_ASCII);
    }
Reads ascii string from input stream. {@link #readVarInt()} will be first
called automatically to understand byte length of the string.

@return non-null ascii string
@throws IOException when failed to read value from input stream, not able to
                    retrieve all bytes, or reached end of the stream
clickhouse-data/src/main/java/com/clickhouse/data/ClickHouseInputStream.java