>>> def sinTay(a):
...     for i in range(15):
...         if   i==0:
...             pass
...         elif i==1:
...             p=a
...         else:
...             p*=a
...         if   i==1:
...             r=a
...         elif i%4==1:
...             r+=p*(1.0/factorial(i))
...         elif i%4==3:
...             r-=p*(1.0/factorial(i))
...     return r
... 
>>> print sin(0)
0.0
>>> print sinTay(0.)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 15, in sinTay
UnboundLocalError: local variable 'r' referenced before assignment