Functions: Return, Scope और Flow

def greet(name):            # void function: no return
    print('Hello', name)

def square(n):              # returns one value
    return n * n

def min_max(seq):           # returns many values as a tuple
    return min(seq), max(seq)

r = greet('Asha')
print(r, square(9), min_max([7, 2, 9]))
low, high = min_max([7, 2, 9])
print(low, high)

def check(n):
    if n % 2 == 0:
        return 'even'
        print('never printed')     # unreachable after return
    return 'odd'

print(check(4), check(7))

def add(a, b):          # line 1
    c = a + b           # line 2
    return c            # line 3

def show():             # line 5
    print('Start')      # line 6
    s = add(3, 4)       # line 7
    print('Sum', s)     # line 8

show()                  # line 10
print('End')            # line 11

x = 'global'

def outer():
    x = 'enclosing'
    def inner():
        print(x)          # not local -> enclosing found first
    inner()

outer()
print(x)

count = 10

def double():
    global count        # refer to the global variable
    count = count * 2

double()
double()
print(count)

c = 10
def g():
    print(c)     # c is local here because of the next line
    c = 5
g()

UnboundLocalError: cannot access local variable 'c' where it is not associated with a value

def update(L, n):
    L.append(n)       # changes the caller's list (mutable)
    n = n + 1         # new local int; caller's int unchanged
    L = [0]           # rebinds local name only
    return n

a = [1]
b = 5
print(update(a, b), a, b)

def increment(x):
    x = x + 1
    return x

def append_item(lst):
    lst += [99]

n = 5
increment(n)
data = [1, 2]
append_item(data)
print(n, data)

def fun(s):
    k = len(s)
    m = ''
    for i in range(0, k):
        if s[i].isupper():
            m = m + s[i].lower()
        elif s[i].isalpha():
            m = m + s[i].upper()
        else:
            m = m + 'bb'
    print(m)

fun('school2@com')