docs: function (name, table, condition, opts) {
              opts = opts || {};
              if (name) {
                  name = sql.stringToIdentifier(name);
                  if (table && condition) {
                      opts = comb.merge({joinType: "left", table: table, condition: condition, column: name}, opts);
                      this._mappedColumns[name] = opts;
                  } else {
                      throw new ModelError("mapped column requires a table and join condition");
                  }
              }
              return this;
          }