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: Albatross Guitars GK014 Semi Hollow Body Electric Guitar
Product feature: Kit includes all parts to build a complete playable semi hollow electric guitar, The body is a basswood top with mahogany sides and quilted maple veneer, Set in neck with adjustable truss rod, All holes are pre-drilled, complete with strings and electric cord
Product brand: Albatross Guitars
Target attributes: Number of Strings
Answer: attribute: number of strings
value: None
source: None