fp.py

from functools import reduce, partial
import itertools as it
from operator import itemgetter, methodcaller

def reversed_partial(f, *args, **kwargs):
    def wrapper(*_args, **_kwargs):
        f(*_args, *args, **_kwargs, **kwargs)
    return wrapper

def unpack(iterable):
    for i in iterable:
        yield from i

def fmap(obj, functions):
    for f in functions:
        yield f(obj)

class Subsequence():
    def __init__(self, sequence):
        self.sequence = sequence
        self.start = 0
        self.finish = len(sequence)

    def upto(self, finish):
        self.finish = self.start + finish
        return self

    def startfrom(self, start):
        self.start += start
        return self

    def between(self, start, finish):
        self.finish = self.start + finish
        self.start += start

    def __getitem__(self, index: int):
        return self.sequence[self.start + index]

    def __len__(self):
        return self.finish - self.start