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: VANS Chukka Low (Material Mash) Navy US Mens (6.5)
Product description: VANS Chukka Low (Material Mash)
Product feature: Canvas, Rubber Sole, Package Dimensions: 12.3 x 7.3 x 4.8 inches, Shipping Weight: 2.1 pounds, ASIN: B00WUMVMQW, Date first listed on Amazon: July 15, 2017, Average Customer Review: 5.0 out of 5 stars 1 customer review
Product brand: Vans
Target attributes: Style
Answer: attribute: style
value: vans
source: product title
attribute: style
value: vans
source: product description
attribute: style
value: vans
source: product brand