code: function setGetter(obj, prop, getter) {
    var key = toPath(arguments);
    return define(obj, key, getter);
  }
docs: Defines a getter function on an object using property path notation.
  
  ```js
  var obj = {};
  getter(obj, 'foo', function() {
  return 'bar';
  });
  ```
  @param {Object} `obj` Object to add property to.
  @param {String|Array} `prop` Property string or array to add.
  @param {Function} `getter` Getter function to add as a property.
  @api public