исходный код numpy _multiarray_umath.py показывает пустые функции

Question

Я хотел создать непрерывную функцию, похожую на numpy.cos ().Но когда я открыл numpy \ core_multiarray_umath.py, все его функции имеют только имя функции и проход, нет реальных кодов для каждой функции, как на самом деле работает numpy:

пример:

Ниже приведена фактическая функция cos от numpy

 def cos(x, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 
"""
cos(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj])    
Cosine element-wise.    
Parameters
----------
x : array_like
    Input array in radians.
out : ndarray, None, or tuple of ndarray and None, optional
    A location into which the result is stored. If provided, it must have
    a shape that the inputs broadcast to. If not provided or `None`,
    a freshly-allocated array is returned. A tuple (possible only as a
    keyword argument) must have length equal to the number of outputs.
where : array_like, optional
    Values of True indicate to calculate the ufunc at that position, values
    of False indicate to leave the value in the output alone.
**kwargs
    For other keyword-only arguments, see the
    :ref:`ufunc docs <ufuncs.kwargs>`.

Returns
-------
y : ndarray
    The corresponding cosine values.
    This is a scalar if `x` is a scalar.

Notes
-----
If `out` is provided, the function writes the result into it,
and returns a reference to `out`.  (See Examples)

References
----------
M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions.
New York, NY: Dover, 1972.

Examples
--------
>>> np.cos(np.array([0, np.pi/2, np.pi]))
array([  1.00000000e+00,   6.12303177e-17,  -1.00000000e+00])
>>>
>>> # Example of providing the optional output parameter
>>> out2 = np.cos([0.1], out1)
>>> out2 is out1
True
>>>
>>> # Example of ValueError due to provision of shape mis-matched `out`
>>> np.cos(np.zeros((3,3)),np.zeros((2,2)))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid return array shape
"""
pass

'' '