def concat_imports(values, sep='.'):
    """Combine import statements.

    Parameters
    ----------
    values : list-like
        The values to be concatenated
    sep : string
        The value between the statements

    Returns
    -------
    str
        The concatenated string

    """
    if len(values) >= 1:
        store = []
        for v in values:
            if isinstance(v, (list, tuple)):
                store.extend(v)
            else:
                store.append(v)
        return sep.join(store)
    else:
        return ''