code: function(properties, value, equals)
    {
      var where = createWhere( properties, value, equals );
  
      for (var i = 0; i < this.length; i++)
      {
        var model = this[ i ];
  
        if ( where( model ) )
        {
          return true;
        }
      }
  
      return false;
    }
docs: Determines whether at least one element in this collection matches the
  given criteria.
  
  ```javascript
  var c = Rekord.collect([{age: 2}, {age: 6}]);
  c.contains('age', 2); // true
  c.contains('age', 3); // false
  c.contains('age'); // true
  c.contains('name'); // false
  ```
  
  @method
  @memberof Rekord.Collection#
  @param {whereInput} [properties] -
  The expression used to create a function to test the elements in this
  collection.
  @param {Any} [value] -
  When the first argument is a string this argument will be treated as a
  value to compare to the value of the named property on the object passed
  through the filter function.
  @param {equalityCallback} [equals=Rekord.equalsStrict] -
  An alternative function can be used to compare to values.
  @return {Boolean} -
  True if any of the elements passed the test function, otherwise false.
  @see Rekord.createWhere