ml/i test -- alter
tests mc-alter (but resets environment so later tests not affected)
mcins%.
mcskip mt,<>
mcalter<to>to< >
mcalter<>as :
mcdef mac1:1
mcalter< > to
mcalter=to a
mcset p1 a 2
mcalter:to as
mcdef mac2 as 3
mcgo error unless mac1%p1.mac2 a 123
mcalter mcalter b to c
c to mcalter a to b
=
mcset p2=6
mcalter,to.
mcins u.ins.
mcskip mt.skip.
ins skip 1..mcsub(x23y.p2-4.p2-3)mcalter.to,
mcins u,inss.
mcskip mt,skipp.
inss skipp 4..mcsub(5,1,0) sb 12345
mcalter space to sp
mcalter n to m
mcalter m to 9
mcalter all to al
mcalter withs to+
mcdef mac3 91 opt sp 91 or end+end al as<%t1.>
mcalter 9 to n
mcalter al to all
mcalter sp to space
mcalter+to withs
mcdef mac4 n1 opt space n1 or end withs end all as<%t1.>
mac4 end end<>mac3  end  end sb 23
try errors (note that on an implementation with alignment the first
 two will not give errors)
1.mcalter=to eq
2.mcalter eq to =
3.mcalter to x
4.mcalter ge to
5.mcalter n to.
6.mcalter ge to g.
7.mcalter , to verylongindeed
 sb 1.2.3.4.5.6.7.
