1 | initial version |

There is no `0`

variable because there is no difference between `0`

and `-0`

. But python lists start with index `0`

. If you want the value of the variable `2`

, you will type:

```
sage: cms()[2]
True
```

Without the `None`

at the beginning (standing for the value of the `0`

variable that does not exist), you will get `False`

(the value of the variable `3`

).

There seems not be any on-line documentation, but you can actually read it from the sage command line, if you type:

```
sage: cms?
```

You will read

```
OUTPUT:
* If this instance is SAT: A tuple of length "nvars()+1" where the
"i"-th entry holds an assignment for the "i"-th variables (the
"0"-th entry is always "None").
```

and

```
First, we do not assume anything, note that the first entry is
"None" because there is not "0"-th variable:
```

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