Yes, compactness in metric spaces is equivalent to being sequentially compact. In metric spaces, compactness is equivalent to being sequentially compact, which means that every sequence in the space has a convergent subsequence. This property is known as the Bolzano-Weierstrass theorem. Therefore, in metric spaces, compactness and sequential compactness are the same concept. **

Some hidden gems in London include the Leighton House Museum, a beautifully preserved Victorian home with stunning Middle Eastern-inspired interiors, and the Hampstead Heath Pergola and Hill Garden, a tranquil and picturesque spot with stunning views of the city. Another hidden gem is the Little Venice area, a peaceful canal network with charming houseboats and waterside cafes. Additionally, the Sir John Soane's Museum, a unique house museum filled with an eclectic collection of art and antiquities, is a must-visit for history and architecture enthusiasts. **

Hidden gems like Kemono Jihen are lesser-known anime series that offer a unique and captivating story, compelling characters, and stunning animation. These hidden gems often fly under the radar but have a dedicated fanbase due to their high-quality storytelling and production. Kemono Jihen, in particular, stands out for its blend of supernatural elements, mystery, and character development, making it a must-watch for fans of the genre. These hidden gems often provide a refreshing and memorable viewing experience for anime enthusiasts looking for something new and different. **

Some short anime hidden gems include "Barakamon," a heartwarming slice-of-life series about a calligrapher finding inspiration in a rural village; "Tatami Galaxy," a unique and visually stunning show about a college student's surreal experiences; and "Anohana: The Flower We Saw That Day," a touching story about a group of friends dealing with grief and guilt. These anime may not be as well-known as some others, but they offer compelling stories and memorable characters that make them worth watching. **

It is likely that the Pioneer vintage compact system will become rare in the future. As time passes, vintage electronics tend to become harder to find as they are either discarded or become collectible items. Additionally, the Pioneer brand has a strong reputation in the audio equipment industry, which could increase the desirability and rarity of their vintage systems. Therefore, it is probable that this Pioneer vintage compact system will become rare as time goes on. **

Some hidden gems for the PC include OBS Studio, a free and open-source software for video recording and live streaming; DaVinci Resolve, a powerful video editing software with advanced features; and HandBrake, a tool for converting video files to different formats. These software are not as well-known as some of the more popular options, but they offer high-quality features and functionality for users looking for alternatives. **

One hidden gem that I would recommend is "Hollow Knight," a beautifully crafted indie game with challenging gameplay and a captivating world to explore. Another hidden gem is "Celeste," a platformer with a touching story and tight controls that make for a rewarding experience. Lastly, "Undertale" is a unique RPG that subverts traditional game mechanics and offers players a thought-provoking narrative. **

Some hidden gems at the Baltic Sea include the Curonian Spit, a narrow strip of land with stunning sand dunes and unique flora and fauna. The island of Gotland in Sweden is also a hidden gem, with its medieval town of Visby and beautiful coastline. The Hel Peninsula in Poland is another hidden gem, offering pristine beaches and charming fishing villages. Finally, the Åland Islands, an autonomous region of Finland, are a hidden gem with their picturesque landscapes and rich maritime history. **