code: def remove_feature(self,var):
          
          if not var:
              raise ValueError("var is None")
          if '"' not in var:
              expr='d:feature[@var="%s"]' % (var,)
          elif "'" not in var:
              expr="d:feature[@var='%s']" % (var,)
          else:
              raise ValueError("Invalid feature name")
  
          l=self.xpath_ctxt.xpathEval(expr)
          if not l:
              return
  
          for f in l:
              f.unlinkNode()
              f.freeNode()
docs: Remove a feature from `self`.
  
          :Parameters:
              - `var`: the feature name.
          :Types:
              - `var`: `unicode`