code: def value(self, value):
          
          # for the indep direction we also allow a string which points to one
          # of the other available dimensions
          # TODO: support c, fc, ec?
          if isinstance(value, common.basestring) and value in ['x', 'y', 'z']:
              # we'll cast just to get rid of any python2 unicodes
              self._value  = str(value)
              dimension = value
              self._unit = getattr(self.call, dimension).unit
              return
  
          # NOTE: cannot do super on setter directly, see this python
          # bug: https://bugs.python.org/issue14965 and discussion:
          # https://mail.python.org/pipermail/python-dev/2010-April/099672.html
          super(CallDimensionI, self)._set_value(value)
docs: set the value