class_docstr: Scope for managing NumPy default dtype semantics.
  In NumPy default dtype semantics, default dtype is 'float64',
  i.e. np.array([1, 2, 3]).dtype = np.float64
  Original default dtype without this semantic is 'float32'.
  
  Do not use this class directly. Use `np_shape(active)` instead.
  
  Example::
  
      with _NumpyDefaultDtypeScope(True):
          y = model(x)
          backward([y])
code: def __enter__(self):
      if self._enter_is_np_default_dtype is not None:
          self._prev_is_np_default_dtype = set_np_default_dtype(
              self._enter_is_np_default_dtype
          )
  
imports: import ctypes
  import functools
  import inspect
  import threading
  import tempfile
  import platform
  from contextlib import contextmanager
  from struct import calcsize
  from .base import _LIB, check_call, c_str, py_str, numeric_types, integer_types, long, _MAX_VALUE_64_BIT_UNSIGNED_, _MAX_VALUE_64_BIT_SIGNED_, _MAX_VALUE_FLOAT32_REPRESENT_
label_desc: Use image node_id 2 for calling the _NumpyDefaultDtypeScope obj's underlying member method code with example usage: obj.__enter__() without return types