parameters: (self, field, error)
docstring: The ``handle_error`` method of a widget must:
  
          - Set the ``error`` attribute of the ``field`` object it is
            passed, if the ``error`` attribute has not already been set.
  
          - Call the ``handle_error`` method of each subfield which also
            has an error (as per the ``error`` argument's ``children``
            attribute).
docstring_summary: The ``handle_error`` method of a widget must:
docstring_tokens: The handle_error method of a widget must :
function: def handle_error(self, field, error):
          """
          The ``handle_error`` method of a widget must:
  
          - Set the ``error`` attribute of the ``field`` object it is
            passed, if the ``error`` attribute has not already been set.
  
          - Call the ``handle_error`` method of each subfield which also
            has an error (as per the ``error`` argument's ``children``
            attribute).
          """
          if field.error is None:
              field.error = error
          for e in error.children:
              for num, subfield in enumerate(field.children):
                  if e.pos == num:
                      subfield.widget.handle_error(subfield, e)
function_tokens: def handle_error ( self , field , error ) : if field . error is None : field . error = error for e in error . children : for num , subfield in enumerate ( field . children ) : if e . pos == num : subfield . widget . handle_error ( subfield , e )