def concat(<EOL>df,<EOL>*,<EOL>columns: List[str],<EOL>new_column: str,<EOL>sep: str = None<EOL>):
if len(columns) < <NUM_LIT:2>:<EOL><INDENT>raise ValueError('<STR_LIT>')<EOL><DEDENT>first_col, *other_cols = columns<EOL>df.loc[:, new_column] = df[first_col].astype(str).str.cat(df[other_cols].astype(str), sep=sep)<EOL>return df<EOL>
Concatenate `columns` element-wise
See [pandas doc](
https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.str.cat.html) for more information

---

### Parameters

*mandatory :*
- `columns` (*list*): list of columns to concatenate (at least 2 columns)
- `new_column` (*str*): the destination column

*optional :*
- `sep` (*str*): the separator