Unsubscribe is a trap, setting up a rule to mark every incoming email from a spamming company's domain as spam automatically is the only thing that works. Or tediously hitting the button manually, for nontechnical users.

Other similar social dance forms from the UK are Contra dancing, English Country dancing, and Ceilidh dancing. Square dancing in the US developed out of these forms. Many other cultures have their own social dance forms, with varying levels of formalization.

Meaningful contribution is easy: these groups always benefit from more participants. Scottish Country dance has a formalized teaching certificate program, roughly equivalent to a Master's degree worth of work (and if you're a UK resident it qualifies to teach PE in UK schools).

We're both wrong. It's a liquid at room temperature, and it's called not petroleum.

You need a >5A output power supply, two voltmeter channels (for source & sink), one ammeter channel (to sense applied load), an electronic DC load (actively cooled FET that uses the ammeter to set a constant current), a microcontroller, screen, some buttons, and software to run the whole thing. Or the manual version: Lab power supply, some USB connector breakout boards, a DC load, optionally a multimeter, a pencil, and some graph paper. Set the power supply current limit over 5A, voltage to 5V, set the DC load to 500mA, and measure the voltage at the power supply & DC load every 100mA as you increase it up to 5A load (or 3A if the cable isn't marked for 5A capability). If the sink drops more than 0.6V below the source, the cable is not compliant.