code: def GetFileList(rootPaths, lstXtn, shortNameOnly='Y'):
      
      numFiles = 0    
      opFileList = []
      if type(rootPaths) == str:
          rootPaths = [rootPaths]
      for rootPath in rootPaths:
          for root, dirs, files in os.walk(rootPath):
              #print('found ' + str(len(dirs)) + ' directories')
              for basename in files:
                  for xtn in lstXtn:
                      if fnmatch.fnmatch(basename, xtn):
                          filename = os.path.join(root, basename)
                          numFiles = numFiles + 1
                          if shortNameOnly == 'Y':
                              opFileList.append( os.path.basename(filename))
                          else:
                              opFileList.append(filename)
                          
      return sorted(opFileList)
docs: builds a list of files and returns as a list