code: def jacobian(self, maps):
          r
          x = maps[self._inputvar]
          # check that x is in bounds
          isin = self._bounds.__contains__(x)
          if isinstance(isin, numpy.ndarray) and not isin.all():
              raise ValueError("one or more values are not in bounds")
          elif not isin:
              raise ValueError("{} is not in bounds".format(x))
          return (self._b - self._a)/((x - self._a)*(self._b - x))
docs: r"""Computes the Jacobian of :math:`y = \mathrm{logit}(x; a,b)`.
  
          This is:
  
          .. math::
  
              \frac{\mathrm{d}y}{\mathrm{d}x} = \frac{b -a}{(x-a)(b-x)},
  
          where :math:`x \in (a, b)`.
  
          Parameters
          ----------
          maps : dict or FieldArray
              A dictionary or FieldArray which provides a map between the
              parameter name of the variable to transform and its value(s).
  
          Returns
          -------
          float
              The value of the jacobian at the given point(s).