How to use the d20.utils.simplify_expr function in d20

# -mi # (#527)
            if mi:
                dice_ast = d20.utils.tree_map(_mi_mapper(mi), dice_ast)

            if d:
                d_ast = d20.parse(d)
                dice_ast.roll = d20.ast.BinOp(dice_ast.roll, '+', d_ast.roll)

            if maxdmg:
                dice_ast = d20.utils.tree_map(_max_mapper, dice_ast)

        rolled = roll(dice_ast)
        if not self.hidden:
            autoctx.meta_queue(f"**{self.name.title()}**: {rolled.result}")

        d20.utils.simplify_expr(rolled.expr)
        autoctx.metavars[self.name] = RerollableStringifier().stringify(rolled.expr.roll)

def consolidated(self):
        """
        Gets the most simplified version of the roll string. Consolidates totals and damage types together.

        Note that this modifies the result expression in place!

        >>> result = vroll("3d6[fire]+1d4[cold]")
        >>> str(result)
        '3d6 (3, 3, 2) [fire] + 1d4 (2) [cold] = `10`'
        >>> result.consolidated()
        '8 [fire] + 2 [cold]'

        :rtype: str
        """
        d20.utils.simplify_expr(self._roll.expr, ambig_inherit='left')
        return RerollableStringifier().stringify(self._roll.expr.roll)

autoctx.meta_queue(f"**Damage Type**: {transforms[None]}")
        elif transforms:
            for frm in transforms:
                autoctx.meta_queue(f"**Damage Change**: {frm} > {transforms[frm]}")

        # evaluate resistances
        do_resistances(dmgroll.expr, resistances, always, transforms)

        # generate output
        result = d20.MarkdownStringifier().stringify(dmgroll.expr)

        # output
        if not hide:
            autoctx.queue(f"**{roll_for}**: {result}")
        else:
            d20.utils.simplify_expr(dmgroll.expr)
            autoctx.queue(f"**{roll_for}**: {d20.MarkdownStringifier().stringify(dmgroll.expr)}")
            autoctx.add_pm(str(autoctx.ctx.author.id), f"**{roll_for}**: {result}")

        autoctx.target.damage(autoctx, dmgroll.total, allow_overheal=self.overheal)

        # return metadata for scripting
        return {'damage': f"**{roll_for}**: {result}", 'total': dmgroll.total, 'roll': dmgroll}