!!! Blocks

This is __Exercise 2__ of the [Micro Python Tutorial].

In Python, a block is a group of statements that belong together, forming the body of a function, loop, class or other structure. A block is defined by an initial line followed by the contents of the block indented four characters.

As an example, a {{for}} block sets up a loop:

%%filename main.py %% %%python
for i in range(0,5):
    print(i)  
%%
Notice that the contents of the {{for}} block are indented four characters. This causes the contents of the block to be executed five times, printing the value of the index variable ("i") each time. 


!! The try-except-finally Block

In Python there is a {{try-except-finally}} structure called a "compound statement" consisting of three separate __blocks__, which is ideal for a main.py file.

In the below example, there is a {{try}} block, followed by an {{except}} block, followed by a {{finally}} block. A {{try}} block must be followed by an {{except}} block and/or a {{finally}} block (you must have one of them).

%%filename main.py %%
%%python
try:

    print('hello world.') # remember to indent the insides of your blocks by 4 characters!

except Exception: 
    # this block is executed if there is an exception (error)
    print('an error occurred.') 
finally:
    # this is always executed, no matter what
    print('complete.')
%%

If you want to use the exception to print out an error message you need to assign it to a variable (in this case, we've used {{ex}}).

%%filename main.py %%
%%python
try:

    print('hello world.')

except Exception as ex:
    print('an error occurred: {}'.format(ex))
finally:
    print('complete.')
%%


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