Each rule definition contains an optional description, a list of variables, and an expression.

每个规则定义含有一个可选描述、变量列表和一个表达式。

youdao

Note: This rule on cutting corners is optional.

说明：切开角的规则是可选的。

youdao

Note: This rule on cutting corners is optional.

说明：切开角的规则是可选的。

youdao