Python function nesting

Nested function:

1, the nested function calls: a function call in the process of a call other functions

# Effect: I Can be a large function, dismantling a plurality of small features, and finally implemented in the major functional, the nested function calls instance 1 as follows: 
# DEF foo (): 
#      bar () 
# foo () 
# nested functions example 2: comparison of four maximum values, ideas: pairwise comparison 
DEF MAX2 (X, Y):
     IF X> Y:
         return X
     the else :
         return Y 

DEF MAX4 (a, B, C, D):
     # step: comparison a, b to give RES1 
    RES1 = MAX2 (a, b)
     # step: Comparative res1, c give RES2 
    RES2 = MAX2 (res1, c)
     # step Three: Comparative res2, d to give RES3 
    RES3 = MAX2 (RES2, D)
     return RES3 

RESMax4 = (1,2,3,4 )
 Print (RES)
 # advantages: clear, less than max4 code.

 

2, the nested function is defined: defined functions within a function

# Examples 1: 
# DEF f1 (): # f1 in the global 
#      DEF f2 (): # f2 locally, how to use the global f2? Currently only the f2 into global 
#          Pass 

# for round: find the circumference, find the area 
# If I only for circular operation, then they would with the nested definitions 
DEF Circle (RADIUS, Action = 0):
     # Import pi function 
    from Math Import pi
     # seeking a circular circumference: 2 * pi * RADIUS 
    DEF perimiter (RADIUS):
         return 2 * pi * RADIUS
     # seeking a circular area: pi * (2 ** RADIUS) 
    DEF area (RADIUS ):
         return PI * (2 ** RADIUS ) 

    IF Action == 0:
        return perimiter (RADIUS)
     elif Action ==. 1 :
         return Area (RADIUS)
     the else :
         Print ( " without this feature !!! " ) 

Circle ( 2, Action = 2)