Chained offset callbacks, at least, have a different order of
parameters than was documented.
during line breaking, for example, when we want to estimate the Y-extent
of a spanner broken at given starting and ending columns.
-If the pure function you're writing takes more than three arguments
-(say, for example, a chained offset callback), this is not a problem:
-just make sure that the grob is the first argument and that start and
-end are the last two arguments.
-
@node How purity is defined and stored
@subsection How purity is defined and stored