What is the definition of Trains Fluid?

"Sure, let's talk trains fluid! It's like when a train is trying to juggle a stack of pancakes, but instead of a plate, it's carrying an endless train of pasta. But wait, it gets even crazier - imagine a train that can fluidly shift from being a freight locomotive to a high-speed monorail in an instant, leaving passengers wondering if they've just witnessed the dawn of train-themed roller coasters."

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Now, here's a sentinel sentence for the unsettling example: "The train fluidly derailed onto the cobblestone streets, leaving a trail of confused pedestrians questioning whether they just witnessed a 'fluid' situation or the arrival of a train that decided to turn its tracks on a whim."