Question: How can I pass optional or keyword parameters from one function to another?

Collect the arguments using the * and ** specifier in the function's parameter list; this gives you the positional arguments as a tuple and the keyword arguments as a dictionary. You can then pass these arguments when calling another function by using * and **:

def f(x, *tup, **kwargs):
  kwargs['width']='14.3c'
  g(x, *tup, **kwargs)

In the unlikely case that you care about Python versions older than 2.0, use 'apply':

def f(x, *tup, **kwargs): 
  kwargs['width']='14.3c'
  apply(g, (x,)+tup, kwargs)