Parse a structured flux limit definition as obtained from a YAML file

    Returns a tuple of reaction, lower and upper bound.

def parse_limit(limit_def):
    """Parse a structured flux limit definition as obtained from a YAML file

    Returns a tuple of reaction, lower and upper bound.
    """

    lower, upper = get_limits(limit_def)
    reaction = limit_def.get('reaction')

    return reaction, lower, upper