fix dispatch and add no_type
add branch typing
check if main exists
check method return type
Todo: SELF_TYPE typing
2phase method name
self return SELF_TYPE
add check_parent_type and fix some small error
static dispatch type fix
more dispatch error fix
self can't be let identifier and add default type for expr
add LUB
multiple self erros
bug fix
add get_symdata
bug fix
make symbol table first, then type checking
fix case typing
new SELF_TYPE
comparision fix