Python ctypes automatically uses RTLD_NOW despite supplied flags. Here's something for fun.

python-dlopen

#!/usr/bin/env python3
'''
test.c - clang -o test.so -fPIC -shared test.c
----------------------------------------------

extern int baz();

int foo() {
  return 42;
}

int bar() {
  return baz();
}

'''
import ctypes
import sys
import os

so = b'./test.so'

def test(mode):
  if mode is os.RTLD_LAZY:
    print('testing RTLD_LAZY\n-----------------')
  else:
    print('\ntesting RTLD_NOW\n----------------')

  FUNKY = ctypes.CFUNCTYPE(ctypes.c_int)

  parent = ctypes.CDLL(None)

  dlopen = parent.dlopen
  dlopen.restype = ctypes.c_void_p

  dlsym = parent.dlsym
  dlsym.restype = ctypes.c_void_p

  lib = dlopen(so, mode)
  if not lib:
    print('error: could not load {}'.format(so.decode('utf-8')))
    if mode is os.RTLD_NOW:
      print('error: missing an undefined function?')
    sys.exit(-1)

  foo = parent.dlsym(lib, b'foo')
  bar = parent.dlsym(lib, b'bar')
  baz = parent.dlsym(lib, b'baz')

  print('foo: {}'.format(hex(foo) if foo else '0x0'))
  print('bar: {}'.format(hex(bar) if bar else '0x0'))
  print('baz: {}'.format(hex(baz) if baz else '0x0'))

  print('calling foo(): {}'.format(FUNKY(foo)()))
  #print('calling bar(): {}'.format(FUNKY(bar)()))

  parent.dlclose(lib)

if __name__ == '__main__':
  for mode in (os.RTLD_LAZY, os.RTLD_NOW):
    test(mode)