code: def find_x(path1):
      '''Return true if substring is in string for files
      in specified path'''
      libs = os.listdir(path1)
      for lib_dir in libs:
          if "doublefann" in lib_dir:
              return Truf find_x(path1):
      '''Return true if substring is in string for files
      in specified path'''
      libs = os.listdir(path1)
      for lib_dir in libs:
          if "doublefann" in lib_dir:
              return True
docs: Return true if substring is in string for files
      in specified path