Why Can't I call base class function for my derived class object?

[snippsat]

To fix and update some stuff
It not a function when it has self,then is a method that belong to the class.
Start using super(),and look at PEP-8

class BaseClass:
    def __init__(self):
        print("This is __init__method of Base Class")

    def base_method1(self):
        print("Only work in Base class <overridden> in DerivedClass")

    def base_method2(self):
        print("my base class method # 2")

class DerivedClass(BaseClass):
    def __init__(self):
        super().__init__()
        print("I am inside my __init__method of my Drived Class")

    def base_method1(self):
        print("DerivedClass class method")

    def derived_method1(self):
        print("I am inside my derived class method 01")

my_inherit = DerivedClass()
my_inherit.base_method2() 

Output:
This is __init__method of Base Class
I am inside my __init__method of my Drived Class
my base class method # 2

---

To take a little about Method overriding,which can be confusing.
See my comment Only work in Base class <overridden> in DerivedClass
So using DerivedClass will base_method1 in BaseClass has no functions as is overridden.

To show a example where both method has same name,but we as add information about date.
This can be called pre-filtering and post-filtering if doing method overriding.

from datetime import datetime

class BaseClass():
    def __init__(self):
        print("This is __init__method of Base Class")

    def base_method1(self, message):
        print(f'base_method1 say {message}')

    def base_method2(self):
        print("My base class method # 2")

class DerivedClass(BaseClass):
    def __init__(self):
        super().__init__()
        print("I am inside my __init__method of my Drived Class")

    def base_method1(self, message):
        date_info = f'at time {datetime.now():%B %d, %Y}'
        super().base_method1(f'{message} {date_info}')

    def derived_method1(self):
        print("I am inside my derived class method 01")

my_inherit = DerivedClass()
my_inherit.base_method2()

Use:

>>> obj = BaseClass()
This is __init__method of Base Class

>>> obj.base_method1('hello')
base_method1 say hello

Now using same base_method1 from DerivedClass,it will add info about date.

>>> obj = DerivedClass()
This is __init__method of Base Class
I am inside my __init__method of my Drived Class

>>> obj.base_method1('hello')
base_method1 say hello at time February 13, 2019