code: def install_tracer(tracer=tracer, pattern=r".*", flags=0):
      
  
      for module in REGISTERED_MODULES:
          if not re.search(pattern, module.__name__, flags=flags):
              continue
  
          trace_module(module, tracer)
      return True
docs: Installs given tracer in the candidates modules for tracing matching given pattern.
  
      :param tracer: Tracer.
      :type tracer: object
      :param pattern: Matching pattern.
      :type pattern: unicode
      :param flags: Matching regex flags.
      :type flags: int
      :return: Definition success.
      :rtype: bool