''' -> """; fix type
''' -> """; fix type

Swapped triple-single-quotes for triple-double-quotes for PEP-8 compliance, and fixed a typo.
HazyResearch/snorkel,jasontlam/snorkel,jasontlam/snorkel,jasontlam/snorkel,HazyResearch/snorkel,HazyResearch/snorkel