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: National Polka Dot Twinset
Product description: Combine 2 shirts in 1 with our Polka Dot Twinset, wear together or separate. This updated customer favorite is a versatile casual shirt includes a polka dot patterned button-front shirt and a contrasting white tank top, making it the perfect match for your favorite slacks and skirts. Its easy-care polyester fabric is lightweight and comfortable, and -length sleeves ensure free movement. * Polyester Shirt and Knit Tank * Button-front with side slits * sleeves with 2 button cuffs * Imported * Machine wash and dry. * Sizes: Misses S, M, L ; Womens 1X, 2X, 3X * Approx. lengths below: Blouse - M 27'', W 28'' ; Tank - M 25'', W 26''
Product feature: 100% Polyester, Polyester Shirt and Knit Tank, Button-front with side slits, sleeves with 2 button cuffs, Imported, Machine wash and dry., Shipping Information: View shipping rates and policies, ASIN: B00IYPKGNY, Item model number: 16152, Date first listed on Amazon: March 12, 2014, Average Customer Review: 4.7 out of 5 stars 4 customer reviews
Product price: $29.95 - $32.95
Product brand: National
Target attributes: Pattern
Answer: attribute: pattern
value: polka dot
source: product title
attribute: pattern
value: polka dot
source: product description