def convert_windows_newlines(file_name):
    """
    Helper function for converting windows newlines in a file as a preprocessing step in case users make samplesheet
    in excel.

    Args:
    file_name (str): name of file to convert to unix newlines.

    """
    with open(file_name) as input:
        file_text = input.read()
    file_text = file_text.replace('\r', '\n')
    with open(file_name, 'w') as output:
        output.write(file_text)
