confuse 2.7
1: s/"\([^"]*\)"/“\1”/g 2: s/`\([^`']*\)'/‘\1’/g 3: s/ '\([^`']*\)' / ‘\1’ /g 4: s/ '\([^`']*\)'$/ ‘\1’/g 5: s/^'\([^`']*\)' /‘\1’ /g 6: s/“”/""/g