Design an extra-long sgRNA array

Build a multiplexed CRISPR array that expresses many sgRNAs from one cassette and shares no long stretch with itself. Twenty sgRNAs built the obvious way carry twenty copies of the same Cas9 scaffold, promoter and terminator — a construct that recombines in the cell and that synthesis vendors refuse — so this draws each transcription unit's parts from the measured non-repetitive collection of Reis et al. (2019), selecting ACROSS promoters, handles and spacers at once rather than within each type, then re-measures the assembled molecule for repeats the junctions created. Returns the sequence, an annotated GenBank file and the pool usage. Takes guides; it does not choose or score them — use crispr_grna_design and crispr_offtarget_check for that.