import sys; print('%s %s' % (sys.executable or sys.platform,
sys.version))
/Library/Frameworks/Python.framework/Versions/7.3/Resources/Python.app/Contents/MacOS/Python
2.7.3 |EPD 7.3-2 (32-bit)| (default, Apr 12 2012, 11:28:34) 
[GCC 4.0.1 (Apple Inc. build 5493)]
x = ['apple','pear','cherry','guava']
'orange' in x
Out[1]: False
'apple' in x
Out[1]: True
xx = x + x
xx
Out[1]: ['apple', 'pear', 'cherry', 'guava', 'apple', 'pear', 'cherry',
'guava']
xx = xx + xx
xx
Out[1]: 
['apple',
 'pear',
 'cherry',
 'guava',
 'apple',
 'pear',
 'cherry',
 'guava',
 'apple',
 'pear',
 'cherry',
 'guava',
 'apple',
 'pear',
 'cherry',
 'guava']
len(xx)
Out[1]: 16
for i in range(10):
    xx = xx + xx

len(xx)
Out[1]: 16384
xx.count('apple')
Out[1]: 4096
for i in range(10):
    xx = xx + xx

len(xx)
Out[1]: 16777216
xx.count('apple')
Out[1]: 4194304
xx.count("orange")
Out[1]: 0
for i in range(10):
    xx = xx + x

len(xx)
Out[1]: 16777256
for i in range(10):
    xx = xx + xx

Traceback (most recent call last):
  File
"/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/IPython/core/interactiveshell.py",
line 2538, in run_code
    exec code_obj in self.user_global_ns, self.user_ns
  File "<ipython-input-1-cdf834081c5a>", line 2, in <module>
    xx = xx + xx
MemoryError
len(xx)
Out[1]: 268436096
xx.count("orange")
Out[1]: 0
import random
import this
The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!
x = ['apple', 'xylophone', 'quince', 'orange']
x
Out[1]: ['apple', 'xylophone', 'quince', 'orange']
sorted(x)
Out[1]: ['apple', 'orange', 'quince', 'xylophone']
x
Out[1]: ['apple', 'xylophone', 'quince', 'orange']
x.sort()
x
Out[1]: ['apple', 'orange', 'quince', 'xylophone']
sorted(x, reverse=True)
Out[1]: ['xylophone', 'quince', 'orange', 'apple']
sorted(x, reverse=False)
Out[1]: ['apple', 'orange', 'quince', 'xylophone']
y = [("apple",5), ("bean", 7), ("quince", 6)]
import operator
sorted(y)
Out[1]: [('apple', 5), ('bean', 7), ('quince', 6)]
y = sorted(x,reverse=True)
y
Out[1]: ['xylophone', 'quince', 'orange', 'apple']
y = [("apple",5), ("bean", 7), ("quince", 6)]
z = sorted(y, reverse=True)
z
Out[1]: [('quince', 6), ('bean', 7), ('apple', 5)]
sorted(z)
Out[1]: [('apple', 5), ('bean', 7), ('quince', 6)]
sorted(z, key=operator.itemgetter(1))
Out[1]: [('apple', 5), ('quince', 6), ('bean', 7)]
sorted(z, key=operator.itemgetter(1),reverse=True)
Out[1]: [('bean', 7), ('quince', 6), ('apple', 5)]
[tup[0] for tup in sorted(z, key=operator.itemgetter(1),reverse=True)]
Out[1]: ['bean', 'quince', 'apple']
thing = sorted(z, key=operator.itemgetter(1),reverse=True)
thing
Out[1]: [('bean', 7), ('quince', 6), ('apple', 5)]
[tup[0] for tup in thing]
Out[1]: ['bean', 'quince', 'apple']

d = {'apple':3,'bear':7,'radio':3}
d.keys()
Out[1]: ['radio', 'apple', 'bear']
d['apple']
Out[1]: 3
d['elephant']
Traceback (most recent call last):
  File
"/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/site-packages/IPython/core/interactiveshell.py",
line 2538, in run_code
    exec code_obj in self.user_global_ns, self.user_ns
  File "<ipython-input-1-aaa0d30344ec>", line 1, in <module>
    d['elephant']
KeyError: 'elephant'
d.get('elephant',77)
Out[1]: 77
w = 'tiger'
if not w in d:
    d[w] = 0
d[w] += 1

d['tiger']
Out[1]: 1
d[w] = d.get(w,0)+1
d[w]
Out[1]: 2
w = 'fox'
d[w] = d.get(w,0)+1
d['fox']
Out[1]: 1