code: function(key, value)
    {
      if ( key in this.indices )
      {
        this.values[ this.indices[ key ] ] = value;
      }
      else
      {
        this.indices[ key ] = this.values.length;
        AP.push.call( this.values, value );
        AP.push.call( this.keys, key );
      }
  
      return this;
    }
docs: Puts the value in the map by the given key.
  
  @param {String} key
  @param {V} value
  @return {Rekord.Map} -
  The reference to this map.