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: DR Strings Electric Guitar Strings, Dimebag Darrell Signature, Treated Nickel-Plated, 10-52
Product description: DR Dimebag Signature on Hex Core Electric Medium Heavy 10-52
Product feature: DR Dimebag Signature on Hex Core Electric Medium Heavy 10-52, DR Dimebag Signature on Hex Core Electric Medium Heavy 10-52, DR Dimebag Signature on Hex Core Electric Medium Heavy 10-52, Hi-Voltage strings are made with a nickel-plated steel wrap on a hex core
Product price: $6.49
Product brand: DR Strings
Target attributes: Core Material
Answer: attribute: core material
value: electric
source: product feature
attribute: core material
value: electric
source: product title
attribute: core material
value: electric
source: product description
attribute: core material
value: steel
source: product feature