def _get(self, numberOfBits: int, doCollect: bool):
        """
        :param numberOfBits: number of bits to get from actual possition
        :param doCollect: if False output is not collected just iterator moves
            in structure
        """
        if not isinstance(numberOfBits, int):
            numberOfBits = int(numberOfBits)

        while self.actuallyHave < numberOfBits:
            # accumulate while not has enought
            try:
                f = next(self.it)
            except StopIteration:
                if self.fillup and self.actual is not None:
                    break
                else:
                    raise NotEnoughtBitsErr()

            thisFieldLen = f._dtype.bit_length()
            if self.actual is None:
                if not doCollect and thisFieldLen <= numberOfBits:
                    numberOfBits -= thisFieldLen
                else:
                    self.actual = f
                    self.actuallyHave = thisFieldLen
            else:
                if not doCollect and self.actuallyHave < numberOfBits:
                    self.actuallyHave = thisFieldLen
                    self.actual = f
                else:
                    self.actuallyHave += thisFieldLen
                    self.actual = f._concat(self.actual)

        # slice out from actual
        actual = self.actual
        actualOffset = self.actualOffset

        if self.actuallyHave < numberOfBits:
            assert self.fillup
            if doCollect:
                t = self.actual._dtype
                fillupW = numberOfBits - self.actuallyHave
                padding_t = Bits(fillupW, signed=t.signed, negated=t.negated)
                padding = padding_t.fromPy(None)
                actual = padding._concat(actual)
            self.actuallyHave = 0

        # update about what was taken
        self.actuallyHave -= numberOfBits
        self.actualOffset += numberOfBits
        if self.actuallyHave == 0:
            self.actual = None
            self.actualOffset = 0

        if doCollect:
            if numberOfBits == 1:
                return actual[actualOffset]
            else:
                return actual[(actualOffset + numberOfBits):actualOffset]
:param numberOfBits: number of bits to get from actual possition
        :param doCollect: if False output is not collected just iterator moves
            in structure