def as_flat_array(iterables):
arr = []<EOL>for x in iterables:<EOL><INDENT>arr.extend(x)<EOL><DEDENT>return np.array(arr)<EOL>
Given a sequence of sequences, return a flat numpy array.

    Parameters
    ----------
    iterables : sequence of sequence of number
        A sequence of tuples or lists containing numbers. Typically these come
        from something that represents each joint in a skeleton, like angle.

    Returns
    -------
    ndarray :
        An array of flattened data from each of the source iterables.