code: def relative_path(self, key):
      '''Returns the relative path for given `key`'''
      key = str(key)                # stringify
      key = key.replace(':', '/')   # turn namespace delimiters into slashes
      key = key[1:]                 # remove first slash (absolute)
      if not self.case_sensitive:
        key = key.lower()           # coerce to lowercase
      return os.path.normpath(keyf relative_path(self, key):
      '''Returns the relative path for given `key`'''
      key = str(key)                # stringify
      key = key.replace(':', '/')   # turn namespace delimiters into slashes
      key = key[1:]                 # remove first slash (absolute)
      if not self.case_sensitive:
        key = key.lower()           # coerce to lowercase
      return os.path.normpath(key)
docs: Returns the relative path for given `key`