import sys

## Boxed arithmetic - overflow handling

def fn():
  i = 0
  while i < 10000000:
      i = i+1







## Introspection and reflection

def fill_list(name):
  # get the frame object of the caller
  frame = sys._getframe().f_back

  # get the variable "name" in the caller's context
  lst = frame.f_locals[name] 
  lst.append(42)

def foo():
  mylist = []
  fill_list("mylist")              
  print mylist               # prints [42]






## Dynamic lookup of methods and attributes

# an empty class
class MyClass:
    pass

# arguments passed to foo can be of any type
def foo(target, flag):
    # the attribute x is set only if flag is True
    if flag:
        target.x = 42

def fn():
    obj = MyClass()
    # if we pass False, obj would not have any attribute x
    foo(obj, True)
    print obj.x
    print getattr(obj, "x")     # use a string for the attribute name





## From Python bytecode to native code
import dis

def add(a, b):
    return a+b

#dis.dis(add)