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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 _scalar_from_string( self, value: str, ) -> Union[Period, Timestamp, Timedelta, NaTType]: """ Construct a scalar type from a string. Parameters value : str Returns ------- Period, Timestamp, or Timedelta, or NaT Whatever the type of ``self._scalar_type`` is. Notes ----- This should call ``self._check_compatible_with`` before unboxing the result. """

        raise AbstractMethodError(self)