frozenset() # Is hashable and can be used as a key in dictionary.
```
### Frozenset
#### Is hashable and can be used as a key in dictionary:
```python
<set> = frozenset()
```
Range
-----
@ -390,7 +395,7 @@ os.popen(<command>).read()
file_name = input('Enter a file name: ')
```
### Print lines until EOF
#### Prints lines until EOF:
```python
while True:
try:
@ -471,9 +476,7 @@ lock.release()
Itertools
---------
#### Every function returns a generator and can accept any collection. If you want to
print an output of generator, as in examples, you need to pass it to _list()_
function.
#### Every function returns a generator and can accept any collection. If you want to print an output of generator, as in examples, you need to pass it to `list()` function.
```python
from itertools import *
@ -541,7 +544,7 @@ islice([1, 2, 3], 1, None)
```
### Ifilter, imap and izip
* #### Filter, map and zip functions that return generators instead of iterators.
#### Filter, map and zip functions that return generators instead of iterators.
Introspection and Metaprograming
@ -586,8 +589,7 @@ False
```
### Type
EEEE Type is the root class. If only passed the object it returns it's type.
Otherwise it creates a new class (and not the instance!).
#### Type is the root class. If only passed the object it returns it's type. Otherwise it creates a new class (and not the instance!):
#### When class is created it checks if it has metaclass defined. If not, it recursively checks if any of his parents has it defined, and eventually comes to type.
#### When class is created it checks if it has metaclass defined. If not, it recursively checks if any of his parents has it defined, and eventually comes to type: