'Recursive helper method to represent value as path in
a hierarchy.
@param value: the value
@param row: the row containing the value
@param rows: all rows from _loopup as dict
@param hierarchy: the S3Hierarchy instance'

def _represent_path(self, value, row, rows=None, hierarchy=None):

    theset = self.theset
    if (value in theset):
        return theset[value]
    prefix = None
    parent = hierarchy.parent(value)
    if parent:
        if (parent in theset):
            prefix = theset[parent]
        elif (parent in rows):
            prefix = self._represent_path(parent, rows[parent], rows=rows, hierarchy=hierarchy)
    result = self.represent_row(row, prefix=prefix)
    theset[value] = result
    return result
