put = async (key, value) => {
    return addOperation({ op: 'PUT', key, value })
  }
Stores a key/value pair to the store.
@function
@param {string} key The key to store.
@param {*} value The value to store.
@return {string} The hash of the new oplog entry.
@memberof module:Databases.Databases-KeyValue
@instance