Distributed version of tree_distance.rfdist
    Parameters: two valid newick strings and a boolean

def rfdist_task(newick_string_a, newick_string_b, normalise, min_overlap=4, overlap_fail_value=0):
    """
    Distributed version of tree_distance.rfdist
    Parameters: two valid newick strings and a boolean
    """
    tree_a = Tree(newick_string_a)
    tree_b = Tree(newick_string_b)
    return treedist.rfdist(tree_a, tree_b, normalise, min_overlap, overlap_fail_value)