Introducing Python

>>> # This is a comment
>>> width = 20
>>> height = 5*9
>>> width * height
900

>>> a=1.5+0.5j
>>> a.real
1.5
>>> a.imag
0.5
>>> abs(a)  # sqrt(a.real**2 + a.imag**2)
5.0

>>> word = 'Help' + 'A'
>>> word
'HelpA'
>>> word[4]
'A'
>>> word[0:2]
'He'
>>> word[-1]     # The last character
'A'

>>> a = ['spam', 'eggs', 100, 1234]
>>> a[0]
'spam'
>>> a[3]
1234
>>> a[-2]
100
>>> a[1:-1]
['eggs', 100]
>>> len(a)
4

# Fibonacci series:
>>> while b < 10:
...       print b
...       a, b = b, a+b
... 
1
1
2
3
5
8

>>>x = int(input("Please enter an integer here: "))
Please enter an integer here:          

>>>if x < 0:
...      print ('the number is negative')
...elif x == 0:
...      print ('the number is zero')
...elif x == 1:
...      print ('the number is one')
...else:
...      print ('More')
...

>>> # Measure some strings:
... a = ['cat', 'window', 'defenestrate']
>>> for x in a:
...     print (x, len(x))
... 
cat 3
window 6
defenestrate 12

>>> def fib(n):    # write Fibonacci series up to n
...     """Print a Fibonacci series up to n."""
...     a, b = 0, 1
...     while b < n:
...         print (b),
...         a, b = b, a+b
... 
>>> # Now call the function we just defined:
... fib(2000)
1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597

>>> import math
>>> math.sin(1)
0.8414709848078965

>>> from math import *
>>> log(1)
0.0

>>> class Complex:
...     def __init__(self, realpart, imagpart):
...         self.r = realpart
...         self.i = imagpart
... 
>>> x = Complex(3.0, -4.5)
>>> x.r, x.i
(3.0, -4.5)