1.看官方文档 https://docs.python.org/3/search.html?q=os&check_keywords=yes&area=default
2.看源码
3.dir()
import requests,os,random
print(dir(random))
# [\'BPF\', \'LOG4\', \'NV_MAGICCONST\', \'RECIP_BPF\', \'Random\', \'SG_MAGICCONST\', \'SystemRandom\', # \'TWOPI\', \'_BuiltinMethodType\', \'_MethodType\', \'_Sequence\', \'_Set\', \'__all__\', \'__builtins__\', # \'__cached__\', \'__doc__\', \'__file__\', \'__loader__\', \'__name__\', \'__package__\', \'__spec__\', \'_acos\', # \'_ceil\', \'_cos\', \'_e\', \'_exp\', \'_inst\', \'_log\', \'_pi\', \'_random\', \'_sha512\', \'_sin\', \'_sqrt\', \'_test\', # \'_test_generator\', \'_urandom\', \'_warn\', \'betavariate\', \'choice\', \'expovariate\', \'gammavariate\', \'gauss\', # \'getrandbits\', \'getstate\', \'lognormvariate\', \'normalvariate\', \'paretovariate\', \'randint\', \'random\', \'randrange\', # \'sample\', \'seed\', \'setstate\', \'shuffle\', \'triangular\', \'uniform\', \'vonmisesvariate\', \'weibullvariate\']