text: [ 'blank', 'definition', 'reference', 'use' ].forEach(function (type) {
    exports[type] = hasProperty(type)
  })
  
  exports.child = hasProperty('form')
  
  exports.component = hasProperty('repository')
  
  exports.form = hasProperty('content')
  
  exports.text = function (argument) {
    return typeof argument === 'string'
  }
  
  function hasProperty (key) {
    return function (argument) {
      return argument.hasOwnProperty(key)
    }
  }
  