Simple For Loop

for i in range (1, 5):		#Start value, Exit value (loop won't run with this value as it exits, so needs to be desired final value + 1)
    print i:

Will output: 1 2 3 4

Reverse Loop

for i in range (5, -1, -1):		#Start value, Exit value (loop won't run with this value as it exits, so needs to be desired final value - 1), adjust value
    print i:

Will output: 5 4 3 2 1 0

Nested For Loops

for level in xrange(255, -1, -1):
    for index in xrange(0, 24):
        led_values[index] = level
    bus.write_i2c_block_data(PCA9626_ADDRESS, (0x80 | PCA9626_REG_PWM0), led_values)
    time.sleep(0.01)

For loop – Each item in a collection

for this_item in my_list:
    #Next item
    print(this_item)


#You can do a loop in 1 line if you wish:
for this_item in my_list: print(this_item)

For loop – Range

for index in range(6):    #Loop 6 times, from value 0 to 5
    #Next index
    print("Loop # " + str(index))

For loop by index

for index in range(0, len(my_array)):
    #Next index
    print("Loop # " + str(my_array[index]))

Loop Control

Exit loop

    break

Exit and start next iteration

    continue