code: def clean_path(a_path, force_os=None, force_start=None):
      
      if not force_start:
          force_start = os.curdir
      if force_os == "windows":
          import ntpath
          return ntpath.relpath(ntpath.normpath(a_path),
                               start=force_start)
      if force_os == "posix":
          import posixpath
          return posixpath.relpath(posixpath.normpath(a_path),
                                  start=force_start)
      return os.path.relpath(os.path.normpath(a_path),
                            start=force_start)
docs: This function is used to normalize the path (of an output or
      dependency) and also provide the path in relative form. It is
      relative to the current working directory