## 8.2 Cells

The module `Cell` contains procedures operating on cells.

`IsCell`

  > `{Cell.is` `+X``` `?B``}`

  tests whether `X` is a cell.

`NewCell`

  > `{Cell.new` `X``` `?Cell``}`

  returns a new cell with initial content `X`.

`Exchange`

  > `{Cell.exchange` `+Cell``` `X``` `Y``}`

  returns the current content of `Cell` in `X`, and sets the content of `Cell` to `Y`.

`Access`

  > `{Cell.access` `+Cell``` `X``}`

  returns the current content of `Cell` in `X`.

`Assign`

  > `{Cell.assign` `+Cell``` `X``}`

  sets the content of `Cell` to `X`.