code: def value_at(self, x, y):
          
          x = Quantity(x, self.xindex.unit).value
          y = Quantity(y, self.yindex.unit).value
          try:
              idx = (self.xindex.value == x).nonzero()[0][0]
          except IndexError as exc:
              exc.args = ("Value %r not found in array xindex" % x,)
              raise
          try:
              idy = (self.yindex.value == y).nonzero()[0][0]
          except IndexError as exc:
              exc.args = ("Value %r not found in array yindex",)
              raise
          return self[idx, idy]
docs: Return the value of this `Series` at the given `(x, y)` coordinates
  
          Parameters
          ----------
          x : `float`, `~astropy.units.Quantity`
              the `xindex` value at which to search
          x : `float`, `~astropy.units.Quantity`
              the `yindex` value at which to search
  
          Returns
          -------
          z : `~astropy.units.Quantity`
              the value of this Series at the given coordinates