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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 CreateDataTypeMap(self, definition_name):
 """Creates a specific data type map by name. Args: definition_name (str):
 name of the data type definition. Returns: DataTypeMap: data type map or None if the date type definition is not available. """

    data_type_definition = self._definitions_registry.GetDefinitionByName(
        definition_name)
    if not data_type_definition:
      return None

    return DataTypeMapFactory.CreateDataTypeMapByType(data_type_definition)