still looking into why comp-phrases is iterating through all possibilities
more diagnostics to avoid ratholes: specifically, don't try to generate phrasal complements where no phrasal complement is possible (i.e. complement of nbar or noun phrase)
appropriate logging for branch
instead of constructing simply lazy seq of parents with heads, construct a lazy seq of maps of parents to parents with heads.
rename map-lexicon to get-lexicon-of-heads
cleanup
add 2 new params to get-parents-with-phrasal-head-map: path-to-here (logging) and lexicon-of-heads (memorized subset of lexicon)
logging: blank path-to-here delimiters
throw exception if rat-hole detected - no possible comp-phrases for head.
whitespace
add function: parents-with-phrasal-complements 
improve function: get-lexicon-of-head-spec
going to use {:comp {:phrasal false}} to indicate when comps cannot be phrasal.
avoiding ratholes finally: creating separate:

parents-with-lexical-head
parents-with-lexical-head-for-comp-phrases

parents-with-phrasal-heads
parents-with-phrasal-heads-for-comp-phrases
cleanup
cleanup
more verbose INFO logging
forest:DEBUG=>INFO
cleanup