class_docstr: Provides common methods for a protocol buffer object.
  
  Wraps a single string value. This makes testing equality easy.
code: def __init__(self, string=""):
      self.string = string
  
file_path: magenta/magenta/common/testing_lib.py
imports: import numpy
  import six
  from google.protobuf import text_format
label_desc: Use image node_id 1 to create a new MockStringProto object from inherited base classes: object with example: obj = MockStringProto(string)