from operator import length_hint

a = [
        [1,2],
        [3,4]
    ]

# 1

print('\n#1\n')

for line in range(len(a)):
    print(a[line])

# 2

print('\n#2\n')

len1=len(a)
i=0
while i<len1:
    print(a[i])
    i+=1

# 2.5

print('\n#2.5\n')

len2=len(a)-1
#len2=len(a)
#len2-=1

while len2>=0:
    print(a[len2])
    len2-=1

# 3

print('\n#3\n')

for curLine in a:
    print(curLine)

# 4

print('\n#4\n')

len3=length_hint(a)
i1=0
while i1<len3:
    print(a[i1])
    i1+=1