some different implementations

sft.py

def sft(x,N=999999999):
    return map(fft,[x]*N)[0]

def sft(x):
    fft_x = fft(x)
    stock_prices = [ticker(stock) for stock in market]
    if stock_prices == fft_x:
       return stock_prices
    else:
       return fft_x