print Substitution("canned","working"); #canned
print Substitution("canned","compiles",'$1 $2','g'); #canned
print Substitution("canned","flawed",'$1 $2'); #canned
print Substitution("canned",".*",`ls`); #first directory entry
`touch down`;
print Substitution("canned",".*",`rm down`); #deleted file