docs: function ( h )
  { getData ( h, true )
    .then
    ( function ( data )
      { if ( h.readValue == data )
        { // same. ignore
        }
        else
        { // console.log ( `onChangedPath ( "${h.path}" ) ` )
          h.evalValue = null
          h.readValue = data
          // reload
          let callbacks = h.callbacks
          for ( let i = callbacks.length-1; i >= 0; --i )
          { let clbk = callbacks [ i ]
            clbk.handler ( h, clbk.callback )
          }
        }
      }
    )
  }