def tokenize_mnemonic(instr):
    """
    Returns a list of tokens
    The first token is the operation and all subsequent tokens are operands
    """

    tokens = instr.mnemonic.split()
    base = tokens[0]
    dst = src = None
    if len(tokens) < 2:
        # Only single token (the operation)
        return ( base ,)

    else:
        op_tks = tokens[1]
        if ',' in op_tks:
            dst, src = op_tks.split(',')
            return (base, dst, src)
        else:
            return (base, op_tks)
    #end if-else on tokens