code: def string_value(node):
      
      if (node.nodeType == node.DOCUMENT_NODE or
          node.nodeType == node.ELEMENT_NODE):
          s = u''
          for n in axes['descendant'](node):
              if n.nodeType == n.TEXT_NODE:
                  s += n.data
          return s
  
      elif node.nodeType == node.ATTRIBUTE_NODE:
          return node.value
  
      elif (node.nodeType == node.PROCESSING_INSTRUCTION_NODE or
            node.nodeType == node.COMMENT_NODE or
            node.nodeType == node.TEXT_NODE):
          return node.data
docs: Compute the string-value of a node.