Buggy python submission (verdict: Runtime Error):
from collections import defaultdict
import sys
sys.setrecursionlimit(100000)

def seq():
    a = 1
    while True:
        yield a
        a += 1

def dfs(here, went, connect, discovery, low, answer, seq):
    went |= {here}
    discovery[here] = low[here] = next(seq)
    child = 0
    for con in connect[here]:
        if con not in went:
            parent[con] = here
            child += 1
            dfs(con, went, connect, discovery, low, answer, seq)
            low[here] = min(low[here], low[con])
            if discovery[here] < low[con]:
                answer[min(here,con)].append(max(here,con))
        elif parent[here] != con:
            low[here] = min(low[here], discovery[con])

vertices, edges = (int(n) for n in input().split(" "))
connect = defaultdict(list)
for _ in range(edges):
    v1, v2 = (int(n) for n in input().split(" "))
    connect[v1].append(v2)
    connect[v2].append(v1)
answer = defaultdict(list)
new_seq = seq()
went = set()
discovery = [0 for n in range(vertices)]
low = [float("inf") for n in range(vertices)]
parent = [None for n in range(vertices)]
dfs(0, went, connect, discovery, low, answer, new_seq)

for k in range(answer.keys()):
    for n in range(answer[k]):
        print(k,n)

Fixed submission:
from collections import defaultdict
import sys
sys.setrecursionlimit(100000)

def seq():
    a = 1
    while True:
        yield a
        a += 1

def dfs(here, went, connect, discovery, low, answer, seq):
    went |= {here}
    discovery[here] = low[here] = next(seq)
    child = 0
    for con in connect[here]:
        if con not in went:
            parent[con] = here
            child += 1
            dfs(con, went, connect, discovery, low, answer, seq)
            low[here] = min(low[here], low[con])
            if discovery[here] < low[con]:
                answer[min(here,con)].append(max(here,con))
        elif parent[here] != con:
            low[here] = min(low[here], discovery[con])

vertices, edges = (int(n) for n in input().split(" "))
connect = defaultdict(list)
for _ in range(edges):
    v1, v2 = (int(n) for n in input().split(" "))
    connect[v1].append(v2)
    connect[v2].append(v1)
answer = defaultdict(list)
new_seq = seq()
went = set()
discovery = [0 for n in range(vertices)]
low = [float("inf") for n in range(vertices)]
parent = [None for n in range(vertices)]
dfs(0, went, connect, discovery, low, answer, new_seq)

for k in sorted(answer.keys()):
    for n in sorted(answer[k]):
        print(k,n)

Buggy python submission (verdict: Runtime Error):
from collections import defaultdict
import sys
sys.setrecursionlimit(100000)

def seq():
    a = 1
    while True:
        yield a
        a += 1

def dfs(here, went, connect, discovery, low, answer, seq):
    went |= {here}
    discovery[here] = low[here] = next(seq)
    child = 0
    for con in connect[here]:
        if con not in went:
            parent[con] = here
            child += 1
            dfs(con, went, connect, discovery, low, answer, seq)
            low[here] = min(low[here], low[con])
            if discovery[here] < low[con]:
                answer[min(here,con)].append(max(here,con))
        elif parent[here] != con:
            low[here] = min(low[here], discovery[con])

vertices, edges = (int(n) for n in input().split(" "))
connect = defaultdict(list)
for _ in range(edges):
    v1, v2 = (int(n) for n in input().split(" "))
    connect[v1].append(v2)
    connect[v2].append(v1)
answer = defaultdict(list)
new_seq = seq()
went = set()
discovery = [0 for n in range(vertices)]
low = [float("inf") for n in range(vertices)]
parent = [None for n in range(vertices)]
dfs(0, went, connect, discovery, low, answer, new_seq)

for k in range(answer.keys()):
    for n in range(answer[k]):
        print(k,n)

Fixed submission:
from collections import defaultdict
import sys
sys.setrecursionlimit(100000)

def seq():
    a = 1
    while True:
        yield a
        a += 1

def dfs(here, went, connect, discovery, low, answer, seq):
    went |= {here}
    discovery[here] = low[here] = next(seq)
    child = 0
    for con in connect[here]:
        if con not in went:
            parent[con] = here
            child += 1
            dfs(con, went, connect, discovery, low, answer, seq)
            low[here] = min(low[here], low[con])
            if discovery[here] < low[con]:
                answer[min(here,con)].append(max(here,con))
        elif parent[here] != con:
            low[here] = min(low[here], discovery[con])

vertices, edges = (int(n) for n in input().split(" "))
connect = defaultdict(list)
for _ in range(edges):
    v1, v2 = (int(n) for n in input().split(" "))
    connect[v1].append(v2)
    connect[v2].append(v1)
answer = defaultdict(list)
new_seq = seq()
went = set()
discovery = [0 for n in range(vertices)]
low = [float("inf") for n in range(vertices)]
parent = [None for n in range(vertices)]
dfs(0, went, connect, discovery, low, answer, new_seq)

for k in sorted(answer.keys()):
    for n in sorted(answer[k]):
        print(k,n)