//Sets the DimensionDefinition for dimension 0 and stores it as a variable.
overworld = setDimensionDefinition(0)

//Adds a BlockReplacement of type "Simple" to the DimensionDefinition variable named "overworld", and configures it to replace stone with diamond blocks.
replacement = overworld.addBlockReplacement("Simple")
replacement.addGenerationPoint("BIOME_BLOCK_REPLACEMENT")
replacement.setBlockToReplace("minecraft:stone")
replacement.setReplacement("minecraft:diamond_block")
replacement.setMaxHeight(255)
replacement.setMinHeight(0)