Is calling method of a class rather than an object of that class/type valid or a thing?

Question

To explain inheritance in Python, the author of a book (by Charles Dierbach) uses the following example of an exploded string class, which takes a string as input (Hello World) and outputs it as H e l l o W o r l d without quotes when the explode() method of the subclass is called:

class ExplodedStr(str):
   def __init__(self, value = ''):
       str.__init__(value)
...

Question: The str.__init___(value) method of class is called rather than method of an object of that type/class. Should I just take this for granted (memorize it) and proceed, or is there a logic?