Why Python allows def functions inside for loop - python-2.7

Question

I'm new at Python, but I tried something and it was ambiguous for me.
Why Python allows doing def of function inside a loop ? and how I can benefit from that ?
for i in range(2):
def f():
print 'f'
f()

Answer 1

Well because python is a high level programming language, you can actually return functions. The following a simple yet demonstrative function.
def multiplier(multiple):
def f(number):
return multiple * number
return f
you can use that function as follows:
double = multiplier(2)
print double(3)
which would print 6.
Same concept would apply for loops if you want to make multiple functions for example and store them in a list or any other purpose befitting your needs.
list_of_functions = [] #list of functions
for i in range(2):
def f(n):
def printer():
print "f"*n
return printer
list_of_functions.append(f(i+1))
Now you can call list_of_functions[0]() which would print 'f' and list_of_functions[1]() which would print 'ff'.

Answer 2

You can define functions anywhere! Because Python is dynamic in this way, you can create functions (and classes, and pretty much anything else) at runtime. It's difficult to come up with a simple example of why you'd want to do this without it seeming contrived, but use cases certainly do exist.
Let's say you're writing a simple processing framework. You'll allow users to type commands, which will cause certain functions to run. You can define those functions first, and then store them all in a dictionary, so that you can quickly look up the appropriate function to run when you get the user's input.
def define_functions(letters):
commands = {} # dictionary of commands
for letter in letters:
# Define functions dynamically
if letter == 'f':
def _function():
print('foo')
elif letter == 'b':
def _function():
print('bar')
elif letter == 'z':
def _function():
print('baz')
else:
def _function():
print('Unknown command')
# Add the new function to the dictionary with the key "n squared"
commands[letter] = _function
return commands
commands = define_functions('abcdefghijklmnopqrstuvwxyz')
# Now we have a dictionary of functions.
while True: # loop forever
# Ask for input and run the specified function!
func_name = raw_input('Enter the one-letter name of the function to run: ')
if func_name not in commands:
print("sorry, that function isn't defined.")
break
# Look up the function
func = commands.get(func_name)
# Call the function
func()