def merge_col_str(
    col_str1, col_str2
):  # merge two multiline strings that represent columns in a table
    """
    Merges two multiline strings that represent columns in a table by
    concatenating each pair of lines.

    Note
    ----
        Both strings must have the same number of lines.

    Parameters
    ----------
        col_str1 : :obj:`str`
            First multiline string.
        col_str2 : :obj:`str`
            Second multiline string.

    Returns
    -------
        :obj:`str`

    """

    return '\n'.join(
        [
            ' '.join([c1, c2])
            for c1, c2 in zip(col_str1.split('\n'), col_str2.split('\n'))
        ]
    )