Problem with storage write to pos 0

I am giving the size too so it is actually like

st.write("f",'xyz',0,10)

while your example would be equal to

st.write("f",'xyz',0,0)

so it is possible to distinguish this, but I get the point.

Maybe allowing this when size is specified all the time (and is nonzero and matches) would make some sense to me - so only 4 parameter variant with nonzero size would support preallocated size use case. But maybe it can be said about three parameter variant too since once you start using offsets it is this case of using preallocated files. So having it as jsvar would make same sense and looks easier to use. So with that it would allow different semantics

• one time write possible = two parameters only
  
• multiple writes with preallocated size - 3 or 4 parameters - in this case writing to any offset including 0 should be possible (as long as data underneath currently written part is all FF).