code: private Environment checkFail(Stmt.Fail stmt, Environment environment, EnclosingScope scope) {
  		return FlowTypeUtils.BOTTOM;
  	}
docs: Type check a fail statement. The environment after a fail statement is
  "bottom" because that represents an unreachable program point.
  
  @param stmt
  Statement to type check
  @param environment
  Determines the type of all variables immediately going into this
  block
  @return