getCodon Get the codon sequence for transcripts in transcriptIdColumn.
getCodon(variantsTable, seqTable, transcriptIdColumn, codonRegion)variants table
cooresponding sequence table from Ensembl DB (either 5' UTR sequence or 3' UTR sequence). Have two columns: ensembl_transcript_id and seq
the name of the transcript id column for the codon region
"startCodon" or "stopCodon"
A list containing codon sequences (NA if the transcript id in that row is NA). If transcriptIdColumn does not exist in the variantsTable, return NA