def opt_in_argv_tail(argv_tail, concise, mnemonic):
    """Say if an optional argument is plainly present"""

    # Give me a concise "-" dash opt, or a "--" double-dash opt, or both

    assert concise or mnemonic
    if concise:
        assert concise.startswith("-") and not concise.startswith("--")
    if mnemonic:
        assert mnemonic.startswith("--") and not mnemonic.startswith("---")

    # Detect the plain use of the concise or mnemonic opts
    # Drop the ambiguities silently, like see "-xh" always as "-x '-h'" never as "-x -h"

    for arg in argv_tail:

        if mnemonic.startswith(arg) and (arg > "--"):
            return True

        if arg.startswith(concise) and not arg.startswith("--"):
            return True

    return False