def first_name(s):
    """
    Returns the first name in s
    
    Examples:
        last_name_first('Walker White') returns 'Walker'
        last_name_first('Walker      White') returns 'Walker'
    
    Parameter s: a name 'first-name last-name'
    Precondition: s is a string 'first-name last-name' with one or more blanks 
    between the two names.
    """
    end_first = s.find(' ')
    return s[:end_first]