python 3.x - Why does urlopen read() produce unexpected behavior -

this naive question because i'm python beginner here goes...

this works...

import urllib.request web=urllib.request.urlopen('ftp://pubftp.spp.org/markets/rtbm/lmp_by_settlement_loc/2015/05/05/') filelist=web.read().decode('utf-8').split('\r\n') 

but doesn't

filelist=urllib.request.urlopen('ftp://pubftp.spp.org/markets/rtbm/lmp_by_settlement_loc/2015/05/05/').read().decode('utf-8').split('\r\n')` 

specifically, either hangs , have cancel command or returns list item 0 empty string

another bit of strange behavior occurs if do

web=urllib.request.urlopen('ftp://pubftp.spp.org/markets/rtbm/lmp_by_settlement_loc/2015/05/05/') web.read() #dumps contents expected web.read() #now displays b'' 

i'm guessing these 2 bits of behavior related , read() changes underlying object reason.

obviously it's easy enough use former syntax i'm sure gotcha come bite me else in future if don't know going on.