def flatten_list(a_list):
    """Given a list of sequences, return a flattened list

    >>> flatten_list([['a', 'b', 'c'], ['e', 'f', 'j']])
    ['a', 'b', 'c', 'e', 'f', 'j']
    >>> flatten_list([['aaaa', 'bbbb'], 'b', 'cc'])
    ['aaaa', 'bbbb', 'b', 'cc']
    """
    # isinstance check to ensure we're not iterating over characters
    # in a string
    return sum([isinstance(item, (list, tuple)) and list(item) or [item] \
        for item in a_list], [])