1. if a function's signature is f `func([]byte)` and we have a string s, then when we call `f([]byte(s))` golang wont create a []byte then copy, in opposite, golang will use the internal byte slice in string.
2. if we use a for range to set every item in slice to a const value, then the for range will be auto turn to memset.
i want to know where i can find all these language optimize, so avoid to do useless human opt again.