text: # Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES.  All rights reserved.
  #
  # 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.
  
  from nemo_text_processing.text_normalization.en.graph_utils import NEMO_NOT_QUOTE, GraphFst
  
  try:
      import pynini
      from pynini.lib import pynutil
  
      PYNINI_AVAILABLE = True
  except (ModuleNotFoundError, ImportError):
      PYNINI_AVAILABLE = False
  
  
  class TelephoneFst(GraphFst):
      """
      Finite state transducer for verbalizing telephone, e.g.
          telephone { number_part: "123-123-5678" }
          -> 123-123-5678 
      """
  
      def __init__(self):
          super().__init__(name="telephone", kind="verbalize")
  
          number_part = pynutil.delete("number_part: \"") + pynini.closure(NEMO_NOT_QUOTE, 1) + pynutil.delete("\"")
          delete_tokens = self.delete_tokens(number_part)
          self.fst = delete_tokens.optimize()
  