code: function getRuleOptionsSchema(rule) {
      const schema = rule.schema || rule.meta && rule.meta.schema;
  
      // Given a tuple of schemas, insert warning level at the beginning
      if (Array.isArray(schema)) {
          if (schema.length) {
              return {
                  type: "array",
                  items: schema,
                  minItems: 0,
                  maxItems: schema.length
              };
          }
          return {
              type: "array",
              minItems: 0,
              maxItems: 0
          };
  
      }
  
      // Given a full schema, leave it alone
      return schema || null;
  }
docs: Gets a complete options schema for a rule.
  @param {{create: Function, schema: (Array|null)}} rule A new-style rule object
  @returns {Object} JSON Schema for the rule's options.