def subst(self, string, dictionary=None):
    """
    Substitutes (via the format operator) the values in the specified
    dictionary into the specified command.

    The command can be an (action, string) tuple.  In all cases, we
    perform substitution on strings and don't worry if something isn't
    a string.  (It's probably a Python function to be executed.)
    """
    if dictionary is None:
      dictionary = self._subst_dictionary
    if dictionary:
      try:
        string = string % dictionary
      except __HOLE__:
        pass
    return string
dataset/ETHPy150Open adblockplus/gyp/gyptest.py/CommandRunner.subst