The code in the tutorials can not run

i run the file fitMutiGraph.C in the tutorials to learn fit a mutigraph.
but when i change the file name(fitMutiGraph.C—> fitMu.C , code is unchanged) . it can’t run!
Error: Function fitMu() is not defined in current scope(0)


it’s because you renamed it. edit the source and change the line void fitMultiGraph() into void fitMu()