is_enumerable

def is_enumerable(collection):
    """Checks if the variable is not a basestring instance and can be
    enumerated.
    """
    try:
        # strings can be iterated - that's not what we want
        if isinstance(collection, basestring):
            return False
        # avoid opening a generator
        if isinstance(collection, types.GeneratorType):
            return True
        for a in collection:
            break
        return True
    except TypeError:
        return False