
The slice method returns a new Blob object with bytes
      ranging from the optional start parameter up to but not including the
      optional end parameter, and with a type
      attribute that is the value of the optional contentType parameter.
| Name | Description | Type | Use | 
|---|---|---|---|
| start | Specifies a value for the start point of a slice call, and must be treated as a byte-order position, with the zeroth position representing the first byte. | int | optional | 
| end | Specifies a value for the end point of a slice call. | int | optional | 
| contentType | Sets a value identical to one that is set with the HTTP/1.1 content-type header on the Blob object returned by the slice call. | int | optional |