def has_duplicates(t):
    """Returns True if any element appears more than once in a sequence.
    t: list    returns: bool
    """
    s = t[:]       # make a copy of t to avoid modifying the parameter
    s.sort()
    
    for i in range(len(s)-1):      
        if s[i] == s[i+1]:          # check for adjacent elements that are equal
            return True
    return False