Optimizing a prime number generator in Python -

i looking suggestions on optimizing prime number generator. please include correction , little comment on why faster in response.

def primelist ( highestnumber ): """ function takes integer , returns list of primes less or equal integer"""      numbers = range( 2, highestnumber + 1 ) # creates inclusive list of numbers between 2 , highestnumber     isprime = [ true ] * len( numbers ) # each element corresponds element in numbers , keeps track of whether or not prime     primes = [] # i'll build list of prime numbers      in range( len( numbers )  ):         if ( isprime[i] == true ):             increment = numbers[i]             position = + increment             primes.append( numbers[ ] )              while ( position < len( numbers )): # execute if above if statement true because position still greater len( number )                 isprime[position] = false  # sets element of isprime false if multiple of lower number                 position += increment        return primes 

there's great discussion on various prime number generators here: fastest way list primes below n

at link python script can use compare algorithm against several others.