def index(self, value, start=None, stop=None):
"""Return the index of the first occurance of C{value} in this
list that is greater than or equal to C{start} and less than
C{stop}. Negative start & stop values are treated like negative
slice bounds -- i.e., they count from the end of the list."""
start, stop = slice_bounds(self, slice(start, stop))
for i, elt in enumerate(islice(self, start, stop)):
if elt == value: return i+start
raise ValueError('index(x): x not in list')
def __getitem__(self, i):
"""
Return the C{i}th token in the corpus file underlying this
corpus view. Negative indices and spans are both supported.
"""
if isinstance(i, slice):
start, stop = slice_bounds(self, i)
return LazySubsequence(self, start, stop)
else:
# Handle negative indices
if i < 0: i += len(self)
if i < 0: raise IndexError('index out of range')
# Use iterate_from to extract it.
try:
return self.iterate_from(i).next()
except StopIteration:
raise IndexError('index out of range')
