def read_header(reader):
    """Reads header and returns the column list.

    This function reads the first row of the CSV file and parses it for the column names.

    Parameters
    ----------
    reader : _csv.reader
        The CSV Reader object to read the header from

    Returns
    -------
    [str,]
        A list with all the column names.
    """
    header = []
    header.extend(col.replace(' ', '_',).upper() for col in next(reader))
    return header