shiftContentOver({ silently = false } = {}): void {
  this.contentTransitionDuration = `${silently ? '0' : this.animDuration}s`;
  this.contentLeft = `-${this.blockWidth}`;
}

shiftContentBack({ silently = false } = {}): void {
  this.contentTransitionDuration = `${silently ? '0' : this.animDuration}s`;
  this.contentLeft = '0';
}

shift(forward: boolean): void {
  if (this.isAnimating) return;
  this.isAnimating = true;
  const coefficient = forward ? this.blocksAtOnce : -1;
  const newBlock = this.blocks.atBeyond(this.index + coefficient);
  this.visibleBlocks.insert(newBlock, forward);
  this.shiftContentOver({ silently: !forward });
  if (!forward) setTimeout(this.shiftContentBack, 0);
  this.index += forward ? 1 : -1;
  setTimeout((): void => {
    this.visibleBlocks.remove(!forward);
    if (forward) this.shiftContentBack({ silently: true });
    this.isAnimating = false;
  }, this.animDuration * 1000);
}

shiftLeft(): void {
  this.shift(true);
}

shiftRight(): void {
  this.shift(false);
}