Marijuana prohibition is history in Canada. Last night, after months of negotiations, Parliament approved a bill to legalize, regulate, and tax marijuana for adults. After one formality — Royal Assent — Canada will become the second nation to end marijuana prohibition and the first G7 country to do so. Regulations vary by province, but most set age limits at 18 or 19 to match the legal age for alcohol and tobacco in Canada. Once the law takes effect, adults can possess up to 30 grams and grow up…