length may not be longer than the size of this.
A reference to this will be held by the newly created Bytes until the byte data is no longer needed.
Since 2.56, if
offset is 0 and
length matches the size of this, then
this will be returned with the reference count incremented by 1. If this is
a slice of another Bytes, then the resulting
Bytes will reference the same Bytes
instead of this. This allows consumers to simplify the usage of
Bytes when asynchronously writing to streams.
offset which subsection starts at
length of subsection
a new Bytes