tidied up model functions with their docs
tidied up model functions with their docs

still untested

joncgoodwin/dfrtopics,agoldst/dfrtopics,joncgoodwin/dfrtopics,agoldst/dfrtopics,joncgoodwin/dfrtopics,agoldst/dfrtopics,agoldst/dfrtopics,agoldst/dfrtopics