Flattens a nested list into a single list

flattenlist.py

# from http://stackoverflow.com/questions/2158395/flatten-an-irregular-list-of-lists-in-python
def flatten(l):
    for el in l:
        if isinstance(el, collections.Iterable) and not isinstance(el, basestring):
            for sub in flatten(el):
                yield sub
        else:
            yield el

# DEPRECATED METHOD THAT WORKS REALLY WELL!
# http://stackoverflow.com/questions/16176742/python-3-replacement-for-deprecated-compiler-ast-flatten-function
# from compiler.ast import flatten
# flatten(["junk",["nested stuff"],[],[[]]])
# ['junk', 'nested stuff']