def create_header(multiobj_bool, constr_func):
    """ Creates header to save data.

    Args:
        multiobj_bool (:obj:`bool`): True if multiobjective function is used.
        constr_func (:obj:`list`)  : Constraint functions applied.
    
    Returns:
        Header.
    """
    if multiobj_bool:
        header = "iter,f0val,fvirg,f0val2,fvirg2"
    else:
        header = "iter,f0val,fvirg"

    for func in constr_func:
        header += ',' + func
    return header