**DEPRECATED**: Evaluate a JavaScript expression in MongoDB.

        :Parameters:
          - `code`: string representation of JavaScript code to be
            evaluated
          - `args` (optional): additional positional arguments are
            passed to the `code` being evaluated

        .. warning:: the eval command is deprecated in MongoDB 3.0 and
          will be removed in a future server version.

def eval(self, code, *args):
        """**DEPRECATED**: Evaluate a JavaScript expression in MongoDB.

        :Parameters:
          - `code`: string representation of JavaScript code to be
            evaluated
          - `args` (optional): additional positional arguments are
            passed to the `code` being evaluated

        .. warning:: the eval command is deprecated in MongoDB 3.0 and
          will be removed in a future server version.
        """
        warnings.warn("Database.eval() is deprecated",
                      DeprecationWarning, stacklevel=2)

        if not isinstance(code, Code):
            code = Code(code)

        result = self.command("$eval", code, args=args)
        return result.get("retval", None)