code: function prop(key) {
      return function(x) {
        var obj = toObject (x);
        if (key in obj) return obj[key];
        throw new TypeError ('‘prop’ expected object to have a property named ' +
                             '‘' + key + '’; ' + show (x) + ' does not');
      };
    }
docs: # prop :: String -> a -> b . . Takes a property name and an object with known properties and returns . the value of the specified property. If for some reason the object . lacks the specified property, a type error is thrown. . . For accessing properties of uncertain objects, use [`get`](#get) instead. . For accessing string map values by key, use [`value`](#value) instead. . . ```javascript . > S.prop ('a') ({a: 1, b: 2}) . 1 . ```