(keys-eqv? ..args)
  args: two or more arguments (any type)
  returns a bool

Returns #t if all of its arguments would occupy the same table entry when used as keys.

This function tests its arguments for "key-equivalence". Key-equivalence is similar to equality, but with a few small differences:

• Numbers and characters are not key-equivalent when their primitive types differ, even if they would be numerically equal.

• All nan.0 floating-point values are key-equivalent to one another.

• When a table is used as a table key, its contents can't be deeply inspected. Two table values are key-equivalent if they share the same identity.

• When testing objects and RData for key-equivalence, their op-eq? methods are ignored.