[plt-scheme] does = really require 2 arguments ?

MzScheme's =, etc. accepted >=1 arguments through version 103.

With version 200, this changed to >=2. The rationale, as I recall:

 * If something like `(= x)' appears in code, it's is likely to be a
   bug. In that case, it's better to report an error than return #t.

 * For `(apply = lst)', it's likely that `lst' starts out as a list of
   numbers (possibly empty), rather of a non-empty list of numbers. So
   already some work is required before deciding to apply `='.

I don't have a strong opinion about >=1 or >=2.

Matthew