def classify_coupling(coupling):
lower, upper = coupling<EOL>if lower is None and upper is None:<EOL><INDENT>return CouplingClass.Uncoupled<EOL><DEDENT>elif lower is None or upper is None:<EOL><INDENT>return CouplingClass.DirectionalReverse<EOL><DEDENT>elif lower == <NUM_LIT:0.0> and upper == <NUM_LIT:0.0>:<EOL><INDENT>return CouplingClass.Inconsistent<EOL><DEDENT>elif lower <= <NUM_LIT:0.0> and upper >= <NUM_LIT:0.0>:<EOL><INDENT>return CouplingClass.DirectionalForward<EOL><DEDENT>elif abs(lower - upper) < <NUM_LIT>:<EOL><INDENT>return CouplingClass.Full<EOL><DEDENT>else:<EOL><INDENT>return CouplingClass.Partial<EOL><DEDENT>
Return a constant indicating the type of coupling.

    Depending on the type of coupling, one of the constants from
    :class:`.CouplingClass` is returned.

    Args:
        coupling: Tuple of minimum and maximum flux ratio