Get a seqlogo for flanking region across three prime end of the genomic range.
Source:R/chip_related.R
      get_three_prime_flank_motif.Rdgiven an object of  GenomicRanges the function generates a seqlogo
of the region flanked around three prime end.
Usage
get_three_prime_flank_motif(
  x,
  y = BSgenome.Hsapiens.UCSC.hg38::BSgenome.Hsapiens.UCSC.hg38,
  extend = 30
)Arguments
- x
 an object of the class GenomicRanges
- y
 an object of class BSgenome, default
BSgenome.Hsapiens.UCSC.hg38::BSgenome.Hsapiens.UCSC.hg38- extend
 an integer, default 30, denoting number of basepairs to extend from three prime end of the range.