1、关于callable详细解说：
Signature: callable(obj, /)
Docstring:
Return whether the object is callable (i.e., some kind of function).
Note that classes are callable, as are instances of classes with a
__call__() method.
Type: builtin_function_or_method
2、具体用法（代码示例）：
>>> import math
>>> x = 1
>>> y = math.sqrt
>>> callable(x)
False
>>> callable(y)
True
作者总结了更全面的解释https://www.cnblogs.com/sesshoumaru/p/5983979.html