Problem in understanding Python list comprehensions

import pickle, urllib

  handle = urllib.urlopen("http://www.pythonchallenge.com/pc/def/banner.p")
  data = pickle.load(handle)
  handle.close()

  for elt in data:
         print "".join([e[1] * e[0] for e in elt])

print "".join([e[1] * e[0] for e in elt])

x = []
for e in elt:
  x.append(e[1] * e[0])
print "".join(x)

>>> data[0]
[(' ', 95)]

>>> ':'.join(['ab', 'cd'])
>>> 'ab:cd'

for elt in data:
    for e in elt:
        print "e[0] == %s, e[1] == %d, which gives us:  '%s'" % (e[0], e[1], ''.join(e[1] * e[0]))

print "".join([e[1] * e[0] for e in elt])

print "".join([e[1] * e[0] for e in elt if len(e) == 2])