Add 'unimplemented' function to indicate unimplemented features
Add 'annStub' function to hide 'unimplemented' function in consturctor of ast elements
Add 'fix several 'astPretty' functions
Fix functions 'flatBlock' and 'prettyBlock'
Fix functions 'fsep' and 'myFsep'
Fix using function 'myFsep'
Fix using function 'traverse' and delete function 'traverseSep'