import csv


def define_column_headers(header_file):
    """
    Import a list of column headers from a csv file and output them as a list to be ready to be set as the column
    headers for a pandas data frame.
    """

    header = []

    with open(header_file) as headerfile:
        contents = csv.reader(headerfile)
        header_list = list(contents)
    
        for item in header_list: 
            header.append(item[0])
            
    return header