text: 'use strict';
  
  var KNOWN_TYPES = ['undefined', 'string', 'number', 'object', 'function', 'boolean', 'symbol'];
  
  module.exports = function defFunc(ajv) {
    defFunc.definition = {
      inline: function (it, keyword, schema) {
        var data = 'data' + (it.dataLevel || '');
        if (typeof schema == 'string') return 'typeof ' + data + ' == "' + schema + '"';
        schema = 'validate.schema' + it.schemaPath + '.' + keyword;
        return schema + '.indexOf(typeof ' + data + ') >= 0';
      },
      metaSchema: {
        anyOf: [
          {
            type: 'string',
            enum: KNOWN_TYPES
          },
          {
            type: 'array',
            items: {
              type: 'string',
              enum: KNOWN_TYPES
            }
          }
        ]
      }
    };
  
    ajv.addKeyword('typeof', defFunc.definition);
    return ajv;
  };
  