code: function getRuleOptionsSchema(id) {
    var rule = rules.get(id),
      schema = rule && rule.schema;
  
    if (!schema) {
      return {
        type: 'array',
        items: [
          {
            'enum': [0, 1, 2]
          }
        ],
        'minItems': 1
      };
    }
  
      // Given a tuple of schemas, insert warning level at the beginning
    if (Array.isArray(schema)) {
      return {
        type: 'array',
        'items': [
          {
            'enum': [0, 1, 2]
          }
        ].concat(schema),
        'minItems': 1,
        'maxItems': schema.length + 1
      };
    }
  
      // Given a full schema, leave it alone
    return schema;
  }
docs: Gets a complete options schema for a rule.
  @param {string} id The rule's unique name.
  @returns {object} JSON Schema for the rule's options.