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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def RegisterHelper(cls, resolver_helper):
 """Registers a path specification resolver helper. Args: resolver_helper (ResolverHelper):
 resolver helper. Raises: KeyError: if resolver helper object is already set for the corresponding type indicator. """

    if resolver_helper.type_indicator in cls._resolver_helpers:
      raise KeyError((
          'Resolver helper object already set for type indicator: '
          '{0!s}.').format(resolver_helper.type_indicator))

    cls._resolver_helpers[resolver_helper.type_indicator] = resolver_helper