# Ex A.1
print( )

# Ex A.2
x += 10

# Ex A.3
' '.join(los)

# Ex A.4
''.join(los)

# Ex A.5
'\n'.join(los)

# Ex A.6
lst2 = lst[:5]

# Ex A.7
x in vowel

# Ex A.8
first = grid[0][0]

# Ex A.9
grid[0][0] = 42

# Ex A.10
line = f.readline().split
print(line.upper())

# Ex A.11
s[::-1].upper()