/fill command amendment

Add a Masked/Mask attribute to the command that takes two coordinates of an area and fills up to a specified block i.e. /fill ~ ~ ~  ~ ~ ~ minecraft:gravel Mask minecraft:grass_block. the example command, when run, would fill the space until it meets a grassblock and stops. it's only quality of life but i think it would be really useful to builders for things like hills and mountains that are rounded/odd shapes instead of doing the layers by hand