We need to be able to change the text once in a while. If
this is non-null, then getText should return this. Note that
start/stop are not affected by changing this.
channel
channel:number = TokenChannels.default
charPositionInLine
charPositionInLine:number = -1
index
index:number = -1
What token number is this from 0..n-1 tokens; < 0 implies invalid index
We need to be able to change the text once in a while. If this is non-null, then getText should return this. Note that start/stop are not affected by changing this.