##########################################################
# file-like objects that save all standard output text in 
# a string, and provide standard input text from a string;
# redirect runs a passed-in function with its output and
# input streams reset to these file-like class objects;
##########################################################

import sys, string                              # get built-in modules

class Output:                                   # simulated output file
    def __init__(self):                                 
        self.text = ''                          # empty string when created
    def write(self, string):                    # add a string of bytes
        self.text = self.text + string            
    def writelines(self, lines):                # add each line in a list
        for line in lines: self.write(line)

class Input:                                    # simulated input file
    def __init__(self, input=''):               # default argument        
        self.text = input                       # save string when created
    def read(self, *size):                      # optional argument
        if not size:                            # read N bytes, or all
            res, self.text = self.text, ''
        else:
            res, self.text = self.text[:size[0]], self.text[size[0]:]
        return res
    def readline(self):
        eoln = string.find(self.text, '\n')     # find offset of next eoln
        if eoln == -1:                          # slice off through eoln
            res, self.text = self.text, ''
        else:
            res, self.text = self.text[:eoln+1], self.text[eoln+1:]
        return res

def redirect(function, args, input):            # redirect stdin/out
    savestreams = sys.stdin, sys.stdout         # run a function object 
    sys.stdin   = Input(input)                  # return stdout text
    sys.stdout  = Output()
    try:
        apply(function, args)
    except:
        sys.stderr.write('error in function! ')
        sys.stderr.write("%s, %s\n" % (sys.exc_type, sys.exc_value))
    result = sys.stdout.text
    sys.stdin, sys.stdout = savestreams
    return result