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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 _validate_target(self, y):
 """ Raises a value error if the target is not a classification target. """

        # Ignore None values
        if y is None:
            return

        y_type = type_of_target(y)
        if y_type not in ("binary", "multiclass"):
            raise YellowbrickValueError((
                "'{}' target type not supported, only binary and multiclass"
            ).format(y_type))