Meta classes - real example

[Mr. Wrobel]

Hi,

I am looking for an example of metaclass usage. Especially I am 
interestet in manipulating instance variables, for example:

My class:
class MrMeta(type):
	pass

class Mr(object):
	__metaclass__ = MrMeta
	
	def __init__(self):
		self.imvariable = 'Zmienna self'

	def aome method(self):
		print 'I am in instance'

So in general, I would like to create a mechanism, that is changing 
value for self.imvariable to capital letters and this should be included 
in my metaclass called MrMeta(type).

Can you guide me please?

Thanks!
Mr. Wrobel