def commandName( self, CmdId=0xFF ):
    """Given an SMB2 command code, return the name of the command.

    Input:
      CmdId - An SMB2/3 command code.

    Output: A string.
            If <CmdId> is a known SMB2/3 command code, the string
            will be the command name.  Otherwise, the empty string
            is returned.
    """
    if( CmdId in self._cmd_LookupDict ):
      return( self._cmd_LookupDict[CmdId] )
    return( '' )