Returns a string representation of given google.protobuf.Value message.

  Args:
    value: google.protobuf.Value message. Assumed to be of type 'number',
      'string' or 'bool'.

def _protobuf_value_to_string(value):
  """Returns a string representation of given google.protobuf.Value message.

  Args:
    value: google.protobuf.Value message. Assumed to be of type 'number',
      'string' or 'bool'.
  """
  value_in_json = json_format.MessageToJson(value)
  if value.HasField("string_value"):
    # Remove the quotations.
    return value_in_json[1:-1]
  return value_in_json