def  METHOD_NAME( self, name, block ):
    if name in self.identifiers:
        # duplicate name!
        sys.stderr.write( "WARNING: duplicate definition for"
                          + " '" + name + "' "
                          + "in " + block.location() + ", "
                          + "previous definition in "
                          + self.identifiers[name].location()
                          + "\n" )
    else:
        self.identifiers[name] = block