Instruction: Parse the product information to locate the target attribute, and then provide the extracted value of the target attribute and its source in the output, specifying None if the attribute is not present.

Input:
Product title: Prismacolor Premier Colored Pencil, Black Grape (3384)
Product description: Popular colored pencils have thick, soft cores made from brilliant, light-resistant pigments.
Product feature: Artist-quality colored pencils for every level of expertise, Colors are easily blended, slow to wear and waterproof, Soft, thick cores create a smooth color laydown for superior blending and shading, High-quality pigments for a rich color saturation, 1 Colored Pencil
Product price: $6.88
Product brand: Prismacolor
Target attributes: Quantity
Answer: attribute: quantity
value: None
source: None