Special keyword value.
The instance of this class may be used as the default value assigned to a
keyword if no other obvious default (e.g., None) is suitable,
Common reasons for using this keyword are:
- A new keyword is added to a function, and that function forwards its
inputs to another function or method which can be defined outside of
NumPy. For example, np.std(x) calls x.std, so when a keepdims
keyword was added that could only be forwarded if the user explicitly
specified keepdims; downstream array libraries may not have added
the same keyword, so adding x.std(..., keepdims=keepdims)
unconditionally could have broken previously working code.
- A keyword is being deprecated, and a deprecation warning must only be
emitted when the keyword is used.