fails:Proc#arity returns -2 for a block taking |(a, b), *c| arguments
fails:Proc#arity returns -1 for a lambda taking one optional argument
fails:Proc#arity returns -2 for a lambda taking |a, b = 0| argument
fails:Proc#arity returns -2 for a lambda taking |a, b = 0, c = 0| argument
fails:Proc#arity returns -2 for a lambda taking |(a, b), c = 0| argument
