for tup in somelist:
    if determine(tup):
         code_to_remove_tup

somelist = [x for x in somelist if determine(x)]

somelist = [x for x in somelist if not determine(x)]

somelist[:] = [x for x in somelist if not determine(x)]

from itertools import ifilterfalse
somelist[:] = list(ifilterfalse(determine, somelist))

somelist[:] = [tup for tup in somelist if determine(tup)]

somelist = [tup for tup in somelist if determine(tup)]

newlist = []
for tup in somelist:
    # lots of code here, possibly setting things up for calling determine
    if determine(tup):
        newlist.append(tup)
somelist = newlist

for tup in somelist[:]:
    # lots of code here, possibly setting things up for calling determine
    if determine(tup):
        newlist.append(tup)

for i in xrange(len(somelist) - 1, -1, -1):
    if some_condition(somelist, i):
        del somelist[i]

>>> somelist[:] = filter(lambda tup: not determine(tup), somelist)
or:
>>> from itertools import ifilterfalse
>>> somelist[:] = list(ifilterfalse(determine, somelist))

for tup in somelist[:]:
    etc....

>>> list = range(10)
>>> for x in list:
...     list.remove(x)
>>> list
[1, 3, 5, 7, 9]

>>> list = range(10)
>>> for x in list[:]:
...     list.remove(x)
>>> list
[]