How to use the d20.utils function in d20

if in_crit:
            dice_ast = d20.utils.tree_map(_crit_mapper, dice_ast)
            if critdice and not autoctx.is_spell:
                # add X critdice to the leftmost node if it's dice
                left = d20.utils.leftmost(dice_ast)
                if isinstance(left, d20.ast.Dice):
                    left.num += int(critdice)

        # -c #
        if c_arg and in_crit:
            c_ast = d20.parse(c_arg)
            dice_ast.roll = d20.ast.BinOp(dice_ast.roll, '+', c_ast.roll)

        # max
        if max_arg:
            dice_ast = d20.utils.tree_map(_max_mapper, dice_ast)

        # evaluate damage
        dmgroll = roll(dice_ast)

        # magic arg (#853)
        always = {'magical'} if (autoctx.is_spell or magic_arg) else None
        # dtype transforms/overrides (#876)
        transforms = {}
        for dtype in dtype_args:
            if '>' in dtype:
                *froms, to = dtype.split('>')
                for frm in froms:
                    transforms[frm.strip()] = to.strip()
            else:
                transforms[None] = dtype
        # display damage transforms (#1103)

level = autoctx.caster.spellbook.caster_level
            if level < 5:
                level_dice = 1
            elif level < 11:
                level_dice = 2
            elif level < 17:
                level_dice = 3
            else:
                level_dice = 4

            def mapper(node):
                if isinstance(node, d20.ast.Dice):
                    node.num = level_dice
                return node

            dice_ast = d20.utils.tree_map(mapper, dice_ast)

        if effect.higher and not autoctx.get_cast_level() == autoctx.spell.level:
            higher = effect.higher.get(str(autoctx.get_cast_level()))
            if higher:
                higher_ast = d20.parse(higher)
                dice_ast.roll = d20.ast.BinOp(dice_ast.roll, '+', higher_ast.roll)

    return dice_ast

def _vroll(dice, multiply=1, add=0, roller=None):
    if roller is None:
        roller = d20.Roller()

    dice_ast = roller.parse(dice)

    if multiply != 1 or add != 0:
        def mapper(node):
            if isinstance(node, d20.ast.Dice):
                node.num = (node.num * multiply) + add
            return node

        dice_ast = d20.utils.tree_map(mapper, dice_ast)

    try:
        rolled = roller.roll(dice_ast)
    except d20.RollError:
        return None
    return SimpleRollResult(rolled)

if mi_arg:
            dice_ast = d20.utils.tree_map(_mi_mapper(mi_arg), dice_ast)

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

        # crit
        in_crit = autoctx.in_crit or crit_arg
        roll_for = "Damage" if not in_crit else "Damage (CRIT!)"
        if in_crit:
            dice_ast = d20.utils.tree_map(_crit_mapper, dice_ast)
            if critdice and not autoctx.is_spell:
                # add X critdice to the leftmost node if it's dice
                left = d20.utils.leftmost(dice_ast)
                if isinstance(left, d20.ast.Dice):
                    left.num += int(critdice)

        # -c #
        if c_arg and in_crit:
            c_ast = d20.parse(c_arg)
            dice_ast.roll = d20.ast.BinOp(dice_ast.roll, '+', c_ast.roll)

        # max
        if max_arg:
            dice_ast = d20.utils.tree_map(_max_mapper, dice_ast)

        # evaluate damage
        dmgroll = roll(dice_ast)

        # magic arg (#853)

d_arg = f"{d_arg}+{effect_d}"
                else:
                    d_arg = effect_d

        # check if we actually need to care about the -d tag
        if self.is_meta(autoctx):
            d_arg = None  # d was likely applied in the Roll effect already

        # set up damage AST
        damage = autoctx.parse_annostr(damage)
        dice_ast = copy.copy(d20.parse(damage))
        dice_ast = _upcast_scaled_dice(self, autoctx, dice_ast)

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

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

        # crit
        in_crit = autoctx.in_crit or crit_arg
        roll_for = "Damage" if not in_crit else "Damage (CRIT!)"
        if in_crit:
            dice_ast = d20.utils.tree_map(_crit_mapper, dice_ast)
            if critdice and not autoctx.is_spell:
                # add X critdice to the leftmost node if it's dice
                left = d20.utils.leftmost(dice_ast)
                if isinstance(left, d20.ast.Dice):
                    left.num += int(critdice)