code: def get_prep_value(self, value):
  		
  		if value is None or value == "":
  			return None
  		if isinstance(value, six.string_types):
  			value = _hex_string_to_unsigned_integer(value)
  		if _using_signed_storage():
  			value = _unsigned_to_signed_integer(value)
  		return value
docs: Return the integer value to be stored from the hex string