Sandwich: a tool for human to curate things given a taxonomy.

Assumptions:

• Taxonomy is a tree. At each level, the categories are mutually exclusive and collectively exhaustive.
• Taxonomy labelling is hierarcial. Allow labeler to work on high level categories first and then move to lower level automatically.
• To err is human. Sandwich manages labeling errors natively via Bayesian rules.
• Cognitive load is real. Sandwich gives labeler a handful of choices each round regardless of the cardinality of labels.