def _set_nameserver_cos(self, v, load=False):
    """
    Setter method for nameserver_cos, mapped from YANG variable /brocade_nameserver_rpc/get_nameserver_detail/output/show_nameserver/nameserver_cos (nameserver-cos-type)
    If this variable is read-only (config: false) in the
    source YANG file, then _set_nameserver_cos is considered as a private
    method. Backends looking to populate this variable should
    do so via calling thisObj._set_nameserver_cos() directly.

    YANG Description: Indicates the Fibre Channel Class of
Service supported by the device.
    """
    if hasattr(v, "_utype"):
      v = v._utype(v)
    try:
      t = YANGDynClass(v,base=RestrictedClassType(base_type=unicode, restriction_dict={'pattern': u'F|1|2|3|,', 'length': [u'0..8']}), is_leaf=True, yang_name="nameserver-cos", rest_name="nameserver-cos", parent=self, path_helper=self._path_helper, extmethods=self._extmethods, register_paths=False, extensions={u'tailf-common': {u'info': u'class of service'}}, namespace='urn:brocade.com:mgmt:brocade-nameserver', defining_module='brocade-nameserver', yang_type='nameserver-cos-type', is_config=True)
    except (TypeError, ValueError):
      raise ValueError({
          'error-string': """nameserver_cos must be of a type compatible with nameserver-cos-type""",
          'defined-type': "brocade-nameserver:nameserver-cos-type",
          'generated-type': """YANGDynClass(base=RestrictedClassType(base_type=unicode, restriction_dict={'pattern': u'F|1|2|3|,', 'length': [u'0..8']}), is_leaf=True, yang_name="nameserver-cos", rest_name="nameserver-cos", parent=self, path_helper=self._path_helper, extmethods=self._extmethods, register_paths=False, extensions={u'tailf-common': {u'info': u'class of service'}}, namespace='urn:brocade.com:mgmt:brocade-nameserver', defining_module='brocade-nameserver', yang_type='nameserver-cos-type', is_config=True)""",
        })

    self.__nameserver_cos = t
    if hasattr(self, '_set'):
      self._set()