Ahhh my maths teacher!
Nobody could understand f(x) so he says, "Consider x to be any variable, maybe y and we could have f of y. Or maybe it's cloud and we could have f of cloud. Alternatively, we could have f of dog. Or my favourite, f of pussy." and he actually drew a pussy cat and said, "Now I want everyone to f pussy for the value of 2"
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Nobody could understand f(x) so he says, "Consider x to be any variable, maybe y and we could have f of y. Or maybe it's cloud and we could have f of cloud. Alternatively, we could have f of dog. Or my favourite, f of pussy." and he actually drew a pussy cat and said, "Now I want everyone to f pussy for the value of 2"
...