def **(other)
      if other.is_a?(Numeric)
        self.class.new(to_hash.merge(:exponent => exponent * other))
      else
        fail TypeError, "Can't raise #{self} to #{other}."
      end
    end
def **(other)
      if other.is_a?(Numeric)
        self.class.new(to_hash.merge(:exponent => exponent * other))
      else
        fail TypeError, "Can't raise #{self} to #{other}."
      end
    end
Term exponentiation. Raise a term to a numeric power.
 params other [Numeric]
 @return [Term]