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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_rows_by_string(tab, names, colnames=['assoc']):
 """Find the rows in a table ``tab`` that match at least one of the strings in ``names``. This method ignores whitespace and case when matching strings. Parameters tab : `astropy.table.Table` Table that will be searched. names : list List of strings. colname : str Name of the table column that will be searched for matching string. Returns ------- mask : `~numpy.ndarray` Boolean mask for rows with matching strings. """

    mask = np.empty(len(tab), dtype=bool)
    mask.fill(False)
    names = [name.lower().replace(' ', '') for name in names]

    for colname in colnames:

        if colname not in tab.columns:
            continue

        col = tab[[colname]].copy()
        col[colname] = defchararray.replace(defchararray.lower(col[colname]).astype(str),
                                        ' ', '')
        for name in names:
            mask |= col[colname] == name
    return mask