bad spec: 'x/y=1,,a/b=2'
false
true
bad spec: 'xxxxxxxxx/yyyy3yyy=1'
false
bad spec: 'xxxxxxxxx//yyyyyyy=1'
false
bad spec: 'xxxxxxxxx/yyyyyyy==1'
false
bad spec: 'inch(es)=1,foot/feet=12,'
false
bad spec: ',inch(es)=1,foot/feet=12'
false