An exaple of an emulation of tm.double.

Only the initial configuration was written by hand.
The vicommands text from tm.double was copied and then repeatedly
pasted.  Here is the resulting sequence of configurations.

<0> 11
 <1>11
 2<1>1
 22<1>
 2<2>2
 21<3>
 2<2>11
 <2>211
 1<3>11
 11<3>1
 111<3>
 11<2>11
 1<2>111
 <2>1111
<2> 1111
<h> 1111