blah

gistfile1.py

def one(iterable, condition=None):
  """True if only one value in the iterable evaluates to True."""
  if condition is None:
    condition = bool
  gen = (i for i in iterable if condition(i))
  try:
    gen.next()
  except StopIteration:
    return False
  try:
    gen.next()
    return False
  except StopIteration:
    return True

def first(iterable, condition=None, sentinel=None):
  gen = (i for i in iterable if (condition is None or condition(i)))
  try:
    return gen.next()
  except StopIteration:
    return sentinel