applies the specified chain of stylesheets (with the specified
transformation parameters) using the "self" object as source
chain - can be a list of transforms, in which case only one
transform run will execute, with the list of transforms
all used such that [a.xsl, b.xsl] is equivalent to
adding an import of b.xsl to a.xsl and applying a.xsl
can also be a list of lists of transforms, in which case
a chain of transforms is run,
one pass for each inner list. The output of each
step in the chain is fed as the input to the next
params - a dictionary giving the overridden top-level parameters
for the transforms
ignorePis - whether or not to ignore <xml-stylesheet processing
instructions in the source document
extParams - a special dictionary of parameters that allows the
processor to communicate special values back to the caller
extModules - a list of modules containing extension function and
element implementations