docs: def environment_exists(self, name=None, prefix=None, abspath=True,
                             log=True):
          """Check if an environment exists by 'name' or by 'prefix'.
  
          If query is by 'name' only the default conda environments directory is
          searched.
          """
          if log:
              logger.debug(str((name, prefix)))
  
          if name and prefix:
              raise TypeError("Exactly one of 'name' or 'prefix' is required.")
  
          if name:
              prefix = self.get_prefix_envname(name, log=log)
  
          if prefix is None:
              prefix = self.ROOT_PREFIX
  
          return os.path.isdir(os.path.join(prefix, 'conda-meta'))