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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_sync_methods(cls):
 """Class decorator to add synchronous methods corresponding to async methods. This modifies the class in place, adding additional methods to it. If a synchronous method of a given name already exists it is not replaced. Args: cls: A class. Returns: The same class, modified in place. """

  for name in cls.__dict__.keys():
    if name.endswith('_async'):
      sync_name = name[:-6]
      if not hasattr(cls, sync_name):
        setattr(cls, sync_name, _make_sync_method(name))
  return cls