code: def _indent(self, element, level=0, prefix="\t"):
          
          element_prefix = "\r\n{0}".format(level * prefix)
  
          if len(element):
              if not element.text or not element.text.strip():
                  element.text = element_prefix + prefix
  
              if not element.tail or not element.tail.strip():
                  element.tail = element_prefix
  
              # Yep, let the "element" variable be overwritten
              # pylint: disable=R1704
              for element in element:
                  self._indent(element, level + 1, prefix)
  
              # Tail of the last child
              if not element.tail or not element.tail.strip():
                  element.tail = element_prefix
  
          else:
              if level and (not element.tail or not element.tail.strip()):
                  element.tail = element_prefix
docs: In-place Element text auto-indent, for pretty printing.
  
          Code from: http://effbot.org/zone/element-lib.htm#prettyprint
  
          :param element: An Element object
          :param level: Level of indentation
          :param prefix: String to use for each indentation