def find(self, name):
        """Find a vgroup given its name, returning its reference
        number if found.

        Args::

          name     name of the vgroup to find

        Returns::

          vgroup reference number

        An exception is raised if the vgroup is not found.

        C library equivalent: Vfind
                                                  """

        refnum = _C.Vfind(self._hdf_inst._id, name)
        if not refnum:
            raise HDF4Error("vgroup not found")
        return refnum