What's `//` in Vyper?

Question

I'm doing some division in vyper (v0.4.0b), but I keep getting this error:

InvalidOperation: Cannot perform decimal division on uint256

  (hint: did you mean `(convert(price, uint256) * ADDITIONAL_FEED_PRECISION) * amount // PRECISION`?)

When my original statement has a single backslash.

Why am I getting this error?

Answer 1

Vyper v0.4.0 replaces the normal (single) division operator with a double slash (//) division operator, as can be seen here, here and here.