class Base:
    """Abstract class Base
    """
    # Attributes:
    dummy = None  # (int) 
    __x = 0  # (int) 
    
    # Operations
    def foo(self, a = 0):
        """function foo
        
        a: int
        
        returns int
        """
        raise NotImplementedError()
    
    def _bar(self, x = 0, y = 0):
        """function bar
        
        x: int
        y: int
        
        returns int
        """
        raise NotImplementedError()
    

from PureAbstract import PureAbstract
from Base import Base

class Derived(Base, PureAbstract):
    """Class Derived
    """
    # Attributes:
    
    # Operations
    def foo(self, a = 0):
        """function foo
        
        a: int
        
        returns int
        """
        return None # should raise NotImplementedError()
    
    def newfoo(self):
        """function newfoo
        
        returns int
        """
        return None # should raise NotImplementedError()
    
    def otherfoo(self):
        """function otherfoo
        
        returns int
        """
        return None # should raise NotImplementedError()
    
    def _bar(self, x = 0, y = 0):
        """function bar
        
        x: int
        y: int
        
        returns int
        """
        return None # should raise NotImplementedError()
    

class PureAbstract:
    """Abstract class PureAbstract
    """
    # Attributes:
    
    # Operations
    def otherfoo(self):
        """function otherfoo
        
        returns int
        """
        raise NotImplementedError()