Thanks to Martijn, I eventually found. This is a complete snippet for Python3.
import sys
import inspect
def f1():
"f1!"
pass
def f3():
"f3!"
pass
def f2():
"f2!"
pass
funcs = [elt[1] for elt in inspect.getmembers(sys.modules[__name__],
inspect.isfunction)]
ordered_funcs = sorted(funcs, key=lambda f: f.__code__.co_firstlineno)
for f in ordered_funcs:
print(f.__doc__)