text: # BEGIN_COPYRIGHT
  #
  # Copyright 2009-2021 CRS4.
  #
  # Licensed under the Apache License, Version 2.0 (the "License"); you may not
  # use this file except in compliance with the License. You may obtain a copy
  # of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  # License for the specific language governing permissions and limitations
  # under the License.
  #
  # END_COPYRIGHT
  
  """
  Convert text to lowercase.
  
  Set --kv-separator to the empty string when running this example.
  """
  
  
  # DOCS_INCLUDE_START
  def mapper(_, record, writer):
      writer.emit("", record.lower())
  