writing dynamic functions in the python interpreter

dynamic function example

Python 2.7.3 (default, Apr 20 2012, 22:44:07) 
[GCC 4.6.3] on linux2
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>>> def print_hello():
...     print 'Hello foo world'
... 
>>> print_hello()
Hello foo world
>>> #some other arbitary function call
... #will result in an error
... foo()
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
NameError: name 'foo' is not defined
>>>