'exec_stmt ::= expr exprlist DUP_TOP EXEC_STMT
exec_stmt ::= expr exprlist EXEC_STMT'

def n_exec_stmt(self, node):

    self.write(self.indent, 'exec    ')
    self.preorder(node[0])
    if (node[1][0] != NONE):
        sep = '    in    '
        for subnode in node[1]:
            self.write(sep)
            sep = ',    '
            self.preorder(subnode)
    self.print_()
    self.prune()
