code: def dtype(self, value):
          
          for (dtype, string) in self._all:
              if string == value:
                  return dtype
  
          return None
docs: Gets the datatype for the given `value` (description).
  
          Args:
              value (str): A text description for any datatype.
  
          Returns:
              numpy.dtype: The matching datatype for the given text.
              None: If no match can be found, `None` will be returned.